COMMUNICATION SYSTEM, SLAVE, CONTROLLER, AND COMMUNICATION METHOD

Abstract

The present invention shortens the time it takes for a frame transmission path to be changed after a network connection abnormality has occurred. A communication system (1) comprises a controller (10) and a plurality of slaves (20) that each have a third input / output port (21) and a fourth input / output port (22). The slaves (20) have a detection unit (25) and a slave transmission control unit (23). The detection unit (25) detects connection abnormalities at the third input / output port (21) and connection abnormalities at the fourth input / output port (22). When the detection unit (25) has detected an abnormality, the slave transmission control unit (23) attempts to transmit a disconnected node notification frame that indicates that a change in connection state has been detected from the third input / output port (21) and the fourth input / output port (22). Upon receiving the disconnected node notification frame, the controller changes a normal frame transmission path.

Description

[Technical Field]

[0001] The present disclosure relates to communication systems. [Background technology]

[0002] Patent Document 1 describes a communication system in which a controller and multiple slaves are connected in a ring configuration. In this communication system, the controller periodically broadcasts a network presence frame to the multiple slaves to check the network connection status. Based on the check results, the system changes the frame transmission path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. WO2010 / 143305 Summary of the Invention

[0004] In the conventional communication system described above, the network connection status can only be confirmed when a network presence frame is transmitted, which means that it can take a long time from the occurrence of a network connection abnormality until the frame transmission path is changed.

[0005] Therefore, an object of the present disclosure is to provide a communication system etc. that can reduce the time it takes from the occurrence of an abnormality in a network connection until the frame transmission path is changed, more than ever before.

[0006] A communication system according to an embodiment of the present disclosure is a communication system including a controller and first to Nth slaves (N is an integer equal to or greater than 2). The controller has a first input / output port, a second input / output port, and a controller transmission control unit. Each of the first to Nth slaves has a third input / output port, a fourth input / output port, a slave transmission control unit, and a detection unit. The first input / output port is connected to the fourth input / output port of the first slave. The third input / output port of the Nth slave is connected to the second input / output port. For any K (K is an integer equal to or greater than 2 and equal to or less than N), the third input / output port of the K-1th slave is connected to the fourth input / output port of the Kth slave. The controller transmission control unit generates and transmits normal frames, receives disconnection-node notification frames, and executes a first controller operation mode and a second controller operation mode. In the first controller operation mode, the normal frame is repeatedly transmitted from the first input / output port. In the second controller operation mode, the normal frame is repeatedly transmitted from the first input / output port and the second input / output port. The slave transmission control unit transmits and receives the normal frame, generates the disconnection-node notification frame, and transmits and receives the disconnection-node notification frame, and executes a first slave operation mode and a second slave operation mode. In the first slave operation mode, when one of the third input / output port and the fourth input / output port receives the normal frame, the normal frame is transmitted from the other of the third input / output port and the fourth input / output port. In the second slave operation mode, when the one input / output port receives the normal frame, the normal frame is transmitted from the one input / output port. The detection unit detects an abnormality related to the connection of the third input / output port and an abnormality related to the connection of the fourth input / output port.When the detection unit detects a connection abnormality of the third input / output port or a connection abnormality of the fourth input / output port while operating in the first slave operation mode, the slave transmission control unit switches from the first slave operation mode to the second slave operation mode. The slave transmission control unit also generates the node-disconnection notification frame indicating that a change in connection status has been detected, and attempts to transmit the node-disconnection notification frame from the third input / output port and the fourth input / output port. At the same time, when one of the input / output ports receives the node-disconnection notification frame, the slave transmission control unit transmits the node-disconnection notification frame from the other input / output port. When the controller transmission control unit operates in the first controller operation mode, and the first input / output port or the second input / output port receives the node-disconnection notification frame, the controller transmission control unit switches from the first controller operation mode to the second controller operation mode.

[0007] A slave according to another aspect of the present disclosure includes a first input / output port, a second input / output port, a slave transmission control unit, and a detection unit. The slave transmission control unit transmits and receives normal frames, generates disconnection-node notification frames, and transmits and receives the disconnection-node notification frames, and executes a first slave operation mode and a second slave operation mode. The first slave operation mode is an operation mode in which, when one of the first input / output port and the second input / output port receives the normal frame, the normal frame is transmitted from the other of the first input / output port and the second input / output port. The second slave operation mode is an operation mode in which, when the one input / output port receives the normal frame, the one input / output port transmits a normal frame based on the normal frame. The detection unit detects an abnormality related to the connection of the first input / output port and an abnormality related to the connection of the second input / output port. When the detection unit detects an abnormality in the connection of the first input / output port or an abnormality in the connection of the second input / output port while operating in the first slave operation mode, the slave transmission control unit switches from the first slave operation mode to the second slave operation mode. The slave transmission control unit also attempts to transmit a disconnection node notification frame indicating that a change in connection status has been detected from the first input / output port and the second input / output port. At the same time, the slave transmission control unit transmits the disconnection node notification frame to the one input / output port. force When the port receives the disconnection node notification frame, it transmits the frame from the other input / output port.

[0008] A controller according to another aspect of the present disclosure includes a first input / output port, a second input / output port, and a controller transmission control unit. The controller transmission control unit generates and transmits a normal frame and executes a first controller operation mode and a second controller operation mode. The first controller operation mode is an operation mode in which the normal frame is repeatedly transmitted from the first input / output port. The second controller operation mode is an operation mode in which the normal frame is repeatedly transmitted from the first input / output port and the second input / output port. When the controller transmission control unit, while operating in the first controller operation mode, receives a disconnection-node notification frame indicating that the first input / output port or the second input / output port has detected a change in connection state, the controller transmission control unit switches from the first controller operation mode to the second controller operation mode.

[0009] A communication method according to another aspect of the present disclosure is a communication method performed by a communication system. The communication system includes a controller and first to Nth slaves (N is an integer equal to or greater than 2). The controller has a first input / output port, a second input / output port, and a controller transmission control unit. Each of the first to Nth slaves has a third input / output port, a fourth input / output port, a slave transmission control unit, and a detection unit. The first input / output port is connected to the fourth input / output port of the first slave. The third input / output port of the Nth slave is connected to the second input / output port. For any K (K is an integer between 2 and N), the third input / output port of the K-1th slave is connected to the fourth input / output port of the Kth slave. In the communication method, the controller transmission control unit generates the normal frame, repeatedly transmits the normal frame from the first input / output port in the first controller operation mode, and repeatedly transmits the normal frame from the first input / output port and the second input / output port in the second controller operation mode. In the first slave operation mode, when one of the third input / output port and the fourth input / output port receives the normal frame, the slave transmission control unit of each of the first to Nth slaves transmits the normal frame from the other input / output port of the third input / output port and the fourth input / output port. Furthermore, in the second slave operation mode, when the one of the input / output ports receives the normal frame, the slave transmission control unit transmits the normal frame from the one of the input / output ports. The detection unit detects an abnormality related to the connection of the third input / output port and an abnormality related to the connection of the fourth input / output port. When the detection unit detects an abnormality related to the connection of the third input / output port or an abnormality related to the connection of the fourth input / output port while operating in the first slave operation mode, the slave transmission control unit switches from the first slave operation mode to the second slave operation mode. At the same time, the slave transmission control unit generates a disconnection-node notification frame indicating that a change in the connection status has been detected, and attempts to transmit the disconnection-node notification frame from the third input / output port and the fourth input / output port. The slave transmission control unit then transmits the disconnection-node notification frame to the one of the input / output ports. forceWhen the first input / output port or the second input / output port receives the disconnection-node notification frame, the controller transmission control unit switches from the first controller operation mode to the second controller operation mode when the first input / output port or the second input / output port receives the disconnection-node notification frame while operating in the first controller operation mode.

[0010] According to the communication system, slave, controller, and communication method relating to the above aspects of the present disclosure, the time it takes from the occurrence of an abnormality in the network connection to the change of the frame transmission path can be reduced more than in the past. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a communication system according to the first embodiment. [Figure 2] FIG. 2 is a block diagram showing an example of the configuration of the controller according to the first embodiment. [Figure 3] FIG. 3 is a block diagram illustrating an example of the configuration of the slave according to the first embodiment. [Figure 4] FIG. 4 is a schematic diagram showing a transmission path of a normal frame. [Figure 5] FIG. 5 is a timing chart showing the transmission and reception timing of normal frames and the operation timing of synchronization timing signals. [Figure 6] FIG. 6 is a schematic diagram showing a transmission path of a normal frame. [Figure 7] FIG. 7 is a timing chart showing the transmission and reception timing of normal frames and the operation timing of synchronization timing signals. [Figure 8] FIG. 8 is a schematic diagram showing a state in which a cable breakage abnormality occurs in the cable according to the first embodiment. [Figure 9] FIG. 9 is a sequence diagram of a first operation according to the first embodiment. [Figure 10] FIG. 10 is a schematic diagram showing a state in which a phi terminal abnormality occurs in the TX phi terminal according to the first embodiment. [Figure 11] FIG. 11 is a sequence diagram of the second operation according to the first embodiment. [Figure 12] FIG. 12 is a schematic diagram showing a state in which a phi terminal abnormality occurs in the RX phi terminal according to the first embodiment. [Figure 13] FIG. 13 is a sequence diagram of the third operation according to the first embodiment. [Figure 14] FIG. 14 is a schematic diagram showing a transmission path of a normal frame. [Figure 15] FIG. 15 is a schematic diagram showing a state in which the cable according to the first embodiment has recovered from a cable breakage abnormality. [Figure 16] FIG. 16 is a sequence diagram of the fourth operation according to the first embodiment. [Figure 17] FIG. 17 is a flowchart illustrating the operation of the slave according to the first embodiment. [Figure 18] FIG. 18 is a flowchart illustrating the operation of the slave according to the first embodiment. [Figure 19] FIG. 19 is a flowchart showing the operation of the controller according to the first embodiment. [Figure 20] FIG. 20 is a block diagram illustrating an example of the configuration of a controller according to the second embodiment. [Figure 21] FIG. 21 is a schematic diagram showing a state in which the slaves are being replaced according to the second embodiment. [Figure 22] FIG. 22 is a schematic diagram showing a state in which a slave according to the second embodiment is being removed. [Figure 23] FIG. 23 is a block diagram showing an example of the configuration of a communication system according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] (How one aspect of the present disclosure was achieved) The inventors conducted extensive research and repeated experiments to find a method for shortening the time it takes for a frame transmission path to be changed after a network connection abnormality occurs in a communication system in which a controller and multiple slaves are connected in a ring configuration. As a result, the inventors discovered that by having each slave detect a network connection abnormality and notify the controller of the detected abnormality, the controller can confirm the occurrence of the network connection abnormality in a relatively short time after the abnormality occurs. Based on this discovery, the inventors then conducted further research and experiments. As a result, they came up with the following communication system, etc.

[0013] A communication system according to an embodiment of the present disclosure is a communication system including a controller and first to Nth slaves (N is an integer equal to or greater than 2). The controller has a first input / output port, a second input / output port, and a controller transmission control unit. Each of the first to Nth slaves has a third input / output port, a fourth input / output port, a slave transmission control unit, and a detection unit. The first input / output port is connected to the fourth input / output port of the first slave. The third input / output port of the Nth slave is connected to the second input / output port. For any K (K is an integer equal to or greater than 2 and equal to or less than N), the third input / output port of the K-1th slave is connected to the fourth input / output port of the Kth slave. The controller transmission control unit generates and transmits normal frames, receives disconnection-node notification frames, and executes a first controller operation mode and a second controller operation mode. In the first controller operation mode, the normal frame is repeatedly transmitted from the first input / output port. In the second controller operation mode, the normal frame is repeatedly transmitted from the first input / output port and the second input / output port. The slave transmission control unit transmits and receives the normal frame, generates the disconnection-node notification frame, and transmits and receives the disconnection-node notification frame, and executes a first slave operation mode and a second slave operation mode. In the first slave operation mode, when one of the third input / output port and the fourth input / output port receives the normal frame, the normal frame is transmitted from the other of the third input / output port and the fourth input / output port. In the second slave operation mode, when the one input / output port receives the normal frame, the normal frame is transmitted from the one input / output port. The detection unit detects an abnormality related to the connection of the third input / output port and an abnormality related to the connection of the fourth input / output port.When the detection unit detects a connection abnormality of the third input / output port or a connection abnormality of the fourth input / output port while operating in the first slave operation mode, the slave transmission control unit switches from the first slave operation mode to the second slave operation mode. The slave transmission control unit also generates the node-disconnection notification frame indicating that a change in connection status has been detected, and attempts to transmit the node-disconnection notification frame from the third input / output port and the fourth input / output port. At the same time, when one of the input / output ports receives the node-disconnection notification frame, the slave transmission control unit transmits the node-disconnection notification frame from the other input / output port. When the controller transmission control unit operates in the first controller operation mode, and the first input / output port or the second input / output port receives the node-disconnection notification frame, the controller transmission control unit switches from the first controller operation mode to the second controller operation mode.

[0014] In the above communication system, when the controller transmission control unit operates in the first controller operation mode and the slave transmission control unit of each slave operates in the first slave operation mode, the transmission path of a normal frame is a transmission path that runs from the controller, in order, through the first slave to the Nth slave, and then back to the controller.

[0015] In this state, if the detection unit in any of the slaves detects an abnormality in the connection of the third input / output port or an abnormality in the connection of the fourth input / output port, the slave transmits a disconnection node notification frame to the controller. This allows the controller to receive the disconnection node notification frame relatively quickly after the occurrence of an abnormality in the network connection. Then, when the controller receives the disconnection node notification frame, the controller transmission control unit switches the operation mode from the first controller operation mode to the second controller operation mode.

[0016] On the other hand, in a slave in which the detection unit detects an abnormality in the connection of the third input / output port or an abnormality in the connection of the fourth input / output port, the slave transmission control unit switches the operating mode from the first slave operating mode to the second slave operating mode.

[0017] As a result, the communication path of the communication frame is changed to a transmission path consisting of two paths, the first path and the second path.

[0018] (First route) A route that starts from the controller, passes through the first slave, the slave just before the point where the connection abnormality has occurred, and then the first slave, and returns to the controller again (i.e., a route that loops back at the slave just before the connection abnormality).

[0019] (Second Route) A route that starts from the controller, passes through the Nth slave, the slave just before the connection abnormality, and the Nth slave, and then returns to the controller (i.e., a route that loops back at the slave just before the point where the connection abnormality occurs).

[0020] In this way, the communication system having the above configuration can reduce the time it takes from when an abnormality occurs in the network connection until the frame transmission path is changed, compared to the conventional system.

[0021] In addition, the disconnection node notification frame may include a node count value indicating an integer value greater than or equal to 0, and the slave transmission control unit may have the following characteristics (1) and (2) when operating in the first slave operation mode.

[0022] (1) When the detection unit detects an abnormality in the connection of the one of the input / output ports, it attempts to transmit a disconnection node notification frame from the one of the input / output ports, the frame including a node count value indicating 0. Then, it attempts to transmit a disconnection node notification frame from the other of the input / output ports, the node count value indicating 1.

[0023] (2) When the one input / output port receives a disconnection node notification frame including a node count value indicating 0, the operation mode is switched from the first slave operation mode to the second slave operation mode. force When a port receives a disconnection node notification frame, it transmits from the other input / output port a disconnection node notification frame containing a node count value obtained by adding 1 to the node count value contained in the disconnection node notification frame.

[0024] The controller may further have an abnormality location determination unit that, when the first input / output port and the second input / output port receive a disconnection node notification frame, identifies the location where the abnormality has occurred based on the node count value contained in the disconnection node notification frame received by the first input / output port and the node count value contained in the disconnection node notification frame received by the second input / output port.

[0025] As a result, even if a connection abnormality occurs that can only be detected by the detection unit of the slave on one side of the location where the abnormality occurred, the slave transmission control unit of the slave on the other side of the location where the abnormality occurred can also switch its operating mode from the first slave operating mode to the second slave operating mode, thereby making it possible to determine the location where the abnormality occurred.

[0026] Furthermore, each of the first to Nth slaves may further include a synchronization timing calculation unit that calculates a synchronization timing signal indicating synchronization timing at which the first to Nth slaves operate in synchronization, based on timing at which the third input / output port or the fourth input / output port receives a normal frame. When an input / output port that receives a normal frame receives a disconnection node notification frame and when the detection unit detects an abnormality in connection of the input / output port that receives the normal frame, the synchronization timing calculation unit may update a calculation method for calculating the synchronization timing signal so that the synchronization timing does not change when an input / output port other than the input / output port receives the normal frame.

[0027] This allows the first to Nth slaves to operate in synchronization even if the transmission path of the normal frame is changed.

[0028] Furthermore, when operating in the first slave operation mode, the slave transmission control unit may include a MACID (Media Access Control ID) of the slave including the slave transmission control unit in a line-disconnection node notification frame that the detection unit attempts to transmit when it detects an abnormality related to the connection of the third input / output port or an abnormality related to the connection of the fourth input / output port.The controller may further include an abnormality type determination unit that, when the first input / output port and the second input / output port receive line-disconnection node notification frames, determines the type of abnormality based on the MACID included in the line-disconnection node notification frame received by the first input / output port and the MACID included in the line-disconnection node notification frame received by the second input / output port.

[0029] This allows the controller to determine the type of abnormality.

[0030] The detection unit may further detect recovery from an abnormality related to the connection of the third I / O port and recovery from an abnormality related to the connection of the fourth I / O port. When the detection unit detects recovery from an abnormality related to the connection of the third I / O port or recovery from an abnormality related to the connection of the fourth I / O port, while operating in the second slave operation mode, the slave transmission control unit may switch the operation mode from the second slave operation mode to the first slave operation mode and transmit a disconnection node notification frame from the third I / O port and the fourth I / O port. When the controller transmission control unit operates in the second controller operation mode, and when the first I / O port or the second I / O port receives a disconnection node notification frame, the controller transmission control unit may switch the operation mode from the second controller operation mode to the first controller operation mode.

[0031] This allows the transmission path to be restored when the connection abnormality is resolved.

[0032] A slave according to another aspect of the present disclosure includes a first input / output port, a second input / output port, a slave transmission control unit, and a detection unit. In a first slave operation mode, the slave transmission control unit transmits a normal frame to the first input / output port and the second input / output port. When one of the input / output ports receives a normal frame, the slave transmission control unit transmits the normal frame from the other of the first input / output port and the second input / output port. Furthermore, in the second slave operation mode, when the one of the input / output ports receives a normal frame, the slave transmission control unit transmits the normal frame from the one of the input / output ports. The detection unit detects an abnormality related to the connection of the first input / output port and 2When the detection unit detects an abnormality in the connection of the first input / output port or the second input / output port while operating in the first slave operation mode, the slave transmission control unit switches the operation mode from the first slave operation mode to the second slave operation mode. At the same time, the slave transmission control unit generates the disconnection node notification frame indicating that a change in the connection state has been detected, and attempts to transmit the disconnection node notification frame from the first input / output port and the second input / output port. The slave transmission control unit sends the disconnection node notification frame to one of the input / output ports. force When the port receives the disconnection node notification frame, it transmits the frame from the other input / output port.

[0033] In the slave having the above configuration, when the detection unit detects an abnormality in the connection of the first input / output port or an abnormality in the connection of the second input / output port, the slave can transmit a disconnection node notification frame. This allows the controller to receive the disconnection node notification frame relatively quickly after the occurrence of an abnormality in the network connection. Then, when the controller receives the disconnection node notification frame, the controller can change the frame transmission path.

[0034] In this way, the slave having the above configuration can reduce the time it takes from when an abnormality occurs in the network connection until the frame transmission path is changed, compared to the conventional method.

[0035] In addition, the disconnection node notification frame may include a node count value indicating an integer value greater than or equal to 0, and the slave transmission control unit may perform the following (1) and (2) when operating in the first slave operation mode. (1) When the detection unit detects an abnormality in the connection of the first input / output port, it attempts to transmit a disconnected node notification frame including a node count value indicating 0 from one of the input / output ports, and attempts to transmit a disconnected node notification frame including a node count value indicating 1 from the other input / output port. (2) Input / output of one of the above port When the one input / output receives a disconnection node notification frame including a node count value indicating 0, the one input / output switches its operation mode from the first slave operation mode to the second slave operation mode. force When a port receives a disconnection node notification frame, A disconnection node notification frame including a node count value obtained by adding 1 to the node count value included in the disconnection node notification frame is transmitted from the other input / output port.

[0036] Furthermore, the communication device may further include a synchronization timing calculation unit that calculates a synchronization timing signal indicating synchronization timing based on timing at which the first input / output port or the second input / output port receives the normal frame. When an input / output port that receives the normal frame receives a disconnection node notification frame and when the detection unit detects an abnormality in connection of the input / output port that receives the normal frame, the synchronization timing calculation unit may update a calculation method for calculating the synchronization timing signal so that the synchronization timing does not change when an input / output port other than the received input / output port receives the normal frame.

[0037] Furthermore, when the slave transmission control unit is operating in the first slave operation mode, the slave transmission control unit may include a MACID (Media Access Control ID) of the slave including the slave transmission control unit in a disconnection node notification frame that the detection unit attempts to transmit when it detects an abnormality in the connection of the first input / output port or an abnormality in the connection of the second input / output port.

[0038] Furthermore, the detection unit may further detect recovery from an abnormality related to the connection of the first I / O port and recovery from an abnormality related to the connection of the second I / O port.When the detection unit detects recovery from an abnormality related to the connection of the first I / O port or recovery from an abnormality related to the connection of the second I / O port while operating in the second slave operation mode, the slave transmission control unit may switch the operation mode from the second slave operation mode to the first slave operation mode.At the same time, the slave transmission control unit may transmit a disconnection node notification frame from the first I / O port and the second I / O port.

[0039] A controller according to another aspect of the present disclosure includes a first input / output port, a second input / output port, and a controller transmission control unit. The controller transmission control unit generates a normal frame, repeatedly transmits the normal frame from the first input / output port in a first controller operation mode, and repeatedly transmits the normal frame from the first input / output port and the second input / output port in a second controller operation mode. Furthermore, when the controller transmission control unit is operating in the first controller operation mode, and the first input / output port or the second input / output port receives a disconnection-node notification frame indicating that a change in connection status has been detected, the controller transmission control unit switches the operation mode from the first controller operation mode to the second controller operation mode.

[0040] The controller having the above configuration can change the communication path of the communication frame by receiving the disconnection note notification frame, without transmitting a network presence frame as in the prior art.

[0041] Therefore, the controller can reduce the time it takes from when an abnormality occurs in the network connection until the frame transmission path is changed, compared to conventional methods.

[0042] The node disconnection notification frame may include a MAC ID. Furthermore, the node disconnection notification frame may include an abnormality type determination unit that, when the first input / output port and the second input / output port receive the node disconnection notification frame, determines the type of abnormality based on the MAC ID included in the node disconnection notification frame received by the first input / output port and the MAC ID included in the node disconnection notification frame received by the second input / output port.

[0043] Furthermore, when operating in the second controller operation mode, when the first input / output port or the second input / output port receives a disconnection node notification frame, the operation mode may be switched from the second controller operation mode to the first controller operation mode.

[0044] A communication method according to another aspect of the present disclosure is a communication method performed by a communication system. The communication system includes a controller and first to Nth slaves (N is an integer equal to or greater than 2). The controller has a first input / output port, a second input / output port, and a controller transmission control unit. Each of the first to Nth slaves has a third input / output port, a fourth input / output port, a slave transmission control unit, and a detection unit. The first input / output port is connected to the fourth input / output port of the first slave. The third input / output port of the Nth slave is connected to the second input / output port. For any K (K is an integer equal to or greater than 2 and equal to or less than N), the third input / output port of the K-1th slave is connected to the fourth input / output port of the Kth slave. In the communication method, the controller transmission control unit generates a normal frame, repeatedly transmits the normal frame from the first input / output port in a first controller operation mode, and repeatedly transmits the normal frame from the first input / output port and the second input / output port in a second controller operation mode. When one of the third input / output port and the fourth input / output port receives a normal frame in the first slave operation mode, the slave transmission control unit of each of the first to Nth slaves transmits the normal frame from the other of the third input / output port and the fourth input / output port. Furthermore, when the one input / output port receives a normal frame in the second slave operation mode, the slave transmission control unit transmits the normal frame from the one input / output port. The detection unit detects an abnormality related to the connection of the third input / output port and an abnormality related to the connection of the fourth input / output port. When the slave transmission control unit is operating in the first slave operation mode, if the detection unit detects an abnormality related to the connection of the third input / output port or an abnormality related to the connection of the fourth input / output port, the slave transmission control unit switches from the first slave operation mode to the second slave operation mode.At the same time, the slave transmission control unit generates a disconnection node notification frame indicating that a change in connection state has been detected, and attempts to transmit the disconnection node notification frame from the third input / output port and the fourth input / output port. Then, when the one input / output port receives the disconnection node notification frame, the slave transmission control unit transmits the same from the other input / output port. When the controller transmission control unit is operating in the first controller operation mode, and the first input / output port or the second input / output port receives a disconnection node notification frame, the controller transmission control unit switches from the first controller operation mode to the second controller operation mode.

[0045] In the above communication method, when the controller transmission control unit operates in the first controller operation mode and the slave transmission control unit of each slave operates in the first slave operation mode, the transmission path of a normal frame is a transmission path that runs from the controller, in order, through the first slave to the Nth slave, and then back to the controller.

[0046] In this state, if the detection unit in any of the slaves detects an abnormality in the connection of the third input / output port or an abnormality in the connection of the fourth input / output port, the slave transmits a disconnection node notification frame to the controller. This allows the controller to receive the disconnection node notification frame relatively quickly after the occurrence of an abnormality in the network connection. Then, when the controller receives the disconnection node notification frame, the controller transmission control unit switches the operation mode from the first controller operation mode to the second controller operation mode.

[0047] On the other hand, for a slave in which the detection unit detects an abnormality in the connection of the third input / output port or an abnormality in the connection of the fourth input / output port, the slave transmission control unit switches the operating mode from the first slave operating mode to the second slave operating mode.

[0048] As a result, the communication path of the communication frame is changed to a transmission path consisting of two paths, the first path and the second path shown below. The first path is a path that starts from the controller, in order, via the first slave, the slave just before the location where the connection abnormality has occurred, the first slave, and then returns to the controller again (i.e., a path that loops back at the slave just before the connection abnormality). The second path is a path that starts from the controller, in order, via the Nth slave, the slave just before the connection abnormality, the Nth slave, and then returns to the controller again (i.e., a path that loops back at the slave just before the location where the connection abnormality has occurred).

[0049] In this way, according to the above communication method, the time required from when an abnormality occurs in the network connection until the frame transmission path is changed can be reduced compared to the conventional method.

[0050] Specific examples of a communication system, a slave, a controller, and a communication method according to one aspect of the present disclosure will be described below with reference to the drawings. Each of the embodiments shown here represents one specific example of the present disclosure. Therefore, the numerical values, shapes, components, the arrangement and connection of the components, steps (processes), and the order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, each figure is a schematic diagram and is not necessarily a precise illustration.

[0051] In addition, the comprehensive or specific aspects of the present disclosure may be realized as a system, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, or may be realized as any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.

[0052] (Embodiment 1) [1-1.Configuration] FIG. 1 is a block diagram showing an example of the configuration of a communication system 1 according to the first embodiment.

[0053] As shown in FIG. 1, the communication system 1 includes a controller 10 having a first input / output port 11 and a second input / output port 12, and a plurality of slaves 20 (corresponding to the first slave 20A, the second slave 20B, and the third slave 20C in FIG. 1) each having a third input / output port 21 and a fourth input / output port 22.

[0054] Here, the description will be given assuming that the plurality of slaves 20 are three, namely, a first slave 20A, a second slave 20B, and a third slave 20C, but the number of the plurality of slaves 20 is not necessarily limited to three. In the following, when there is no need to explicitly distinguish between the first slave 20A, the second slave 20B, and the third slave 20C, the first slave 20A, the second slave 20B, and the third slave 20C will also be simply referred to as slaves 20.

[0055] As shown in FIG. 1 , the first input / output port 11 and the fourth input / output port 22 of the first slave 20A are connected by a cable 30A. The third input / output port 21 of the first slave 20A and the fourth input / output port 22 of the second slave 20B are connected by a cable 30B. The third input / output port 21 of the second slave 20B and the fourth input / output port 22 of the third slave 20C are connected by a cable 30C. The third input / output port 21 of the third slave 20C and the second input / output port 12 are connected by a cable 30D. Hereinafter, when there is no need to explicitly distinguish between the cables 30A, 30B, 30C, and 30D, the cables 30A, 30B, 30C, and 30D will also be simply referred to as cables 30.

[0056] The first input / output port 11 has a transmitting terminal TX111 and a receiving terminal RX112. The second input / output port 12 has a transmitting terminal TX121 and a receiving terminal RX122. The third input / output port 21 has a transmitting terminal TX211 and a receiving terminal RX212. The fourth input / output port 22 has a transmitting terminal TX221 and a receiving terminal RX222.

[0057] The cable 30 has a first connection path and a second connection path, and the first connection path connects the transmitting terminal TX111 and the receiving terminal RX222, the transmitting terminal TX121 and the receiving terminal RX212, or the transmitting terminal TX221 and the receiving terminal RX212, and the second connection path connects the transmitting terminal TX221 and the receiving terminal RX112, the transmitting terminal TX211 and the receiving terminal RX122, or the transmitting terminal TX211 and the receiving terminal RX222.

[0058] FIG. 2 is a block diagram showing an example of the configuration of the controller 10. As shown in FIG.

[0059] As shown in FIG. 2, the controller 10 has a first input / output port 11, a second input / output port 12, a controller transmission control unit 13, an abnormality position determination unit 14, and an abnormality type determination unit 15.

[0060] The first input / output port 11 includes a connector 110 having a transmission terminal TX111 and a reception terminal RX112, and a PHY .

[0061] Phi 130 has a TX Phi terminal 131 and an RX Phi terminal 132, and transmits frames to a connected communication device from the TX Phi terminal 131, and receives frames from the connected communication device at the RX Phi terminal 132. The TX Phi terminal 131 is connected to the transmit terminal TX111, and the RX Phi terminal 132 is connected to the receive terminal RX112.

[0062] Furthermore, the Phi 130 detects the link between the RX Phi terminal 132 and the communication device to which it is connected.

[0063] The second input / output port 12 has a connector 120 having a transmitting terminal TX 121 and a receiving terminal RX 122, and a phi 150.

[0064] Phi 150 has a TX Phi terminal 151 and an RX Phi terminal 152, and transmits frames to a connected communication device from the TX Phi terminal 151, and receives frames from the connected communication device at the RX Phi terminal 152. The TX Phi terminal 151 is connected to the transmit terminal TX121, and the RX Phi terminal 152 is connected to the receive terminal RX122.

[0065] The Phi 150 also detects the link between the RX Phi terminal 152 and the communication device to which it is connected.

[0066] The controller transmission control unit 13 operates in a first controller operation mode or a second controller operation mode. In the initial state, the controller transmission control unit 13 operates in the first controller operation mode.

[0067] In the first controller operation mode, the controller transmission control unit 13 repeatedly transmits normal frames from the first input / output port 11. More specifically, in the first controller operation mode, the controller transmission control unit 13 controls the Phi 130 to repeatedly transmit normal frames from the TX Phi terminal 131 to the communication device to which it is connected.

[0068] For example, in the first controller operation mode, the controller transmission control unit 13 may transmit a normal frame from the first input / output port 11 at predetermined intervals.

[0069] In the second controller operation mode, the controller transmission control unit 13 repeatedly transmits normal frames from the first input / output port 11 and the second input / output port 12. More specifically, in the second controller operation mode, the controller transmission control unit 13 controls Phi 130 and Phi 150 to repeatedly transmit normal frames from the TX Phi terminal 131 and the TX Phi terminal 151 to the communication devices to which they are connected.

[0070] For example, in the second controller operation mode, the controller transmission control unit 13 may transmit normal frames from the first input / output port 11 and the second input / output port 12 at predetermined intervals.

[0071] When the controller transmission control unit 13 is operating in the first controller operation mode, if the first input / output port 11 or the second input / output port 12 receives a disconnection node notification frame (described later), the controller transmission control unit 13 switches the operation mode from the first controller operation mode to the second controller operation mode.

[0072] When the controller transmission control unit 13 is operating in the second controller operation mode, if the first input / output port 11 or the second input / output port 12 receives a disconnection node notification frame, the controller transmission control unit 13 switches the operation mode from the second controller operation mode to the first controller operation mode.

[0073] The controller transmission control unit 13 may be realized by, for example, the processor 101 of the controller 10 executing a program stored in the memory 102 of the controller 10.

[0074] When the first input / output port 11 and the second input / output port 12 receive disconnection node notification frames, the abnormality position determination unit 14 determines the location of the occurrence of the abnormality based on the node count value, which is included in the disconnection node notification frames and indicates an integer value equal to or greater than 0. Details of the operation performed by the abnormality position determination unit 14 will be described later.

[0075] The abnormality position determination unit 14 may be realized, for example, by the processor 101 of the controller 10 executing a program stored in the memory 102 of the controller 10.

[0076] When the first input / output port 11 and the second input / output port 12 receive disconnection node notification frames, the abnormality type determination unit 15 determines the type of abnormality based on the MAC ID of the slave 20 included in the disconnection node notification frames. Details of the operation performed by the abnormality type determination unit 15 will be described later.

[0077] The abnormality type determination unit 15 may be realized, for example, by the processor 101 of the controller 10 executing a program stored in the memory 102 of the controller 10.

[0078] FIG. 3 is a block diagram showing an example of the configuration of the slave 20. As shown in FIG.

[0079] As shown in FIG. 3, the slave 20 includes a third input / output port 21, a fourth input / output port 22, a slave transmission control unit 23, a synchronization timing calculation unit 24, and a detection unit 25.

[0080] The third input / output port 21 has a connector 210 having a transmitting terminal TX 211 and a receiving terminal RX 212 , and a phi 230 .

[0081] Phi 230 has a TX Phi terminal 231 and an RX Phi terminal 232, and transmits frames to a connected communication device from the TX Phi terminal 231, and receives frames from the connected communication device at the RX Phi terminal 232. The TX Phi terminal 231 is connected to the transmitting terminal TX211, and the RX Phi terminal 232 is connected to the receiving terminal RX212.

[0082] Furthermore, the Phi 230 detects the link between the RX Phi terminal 232 and the communication device to which it is connected.

[0083] The fourth input / output port 22 has a connector 220 having a transmitting terminal TX221 and a receiving terminal RX222, and a phi 250.

[0084] Phi 250 has a TX Phi terminal 251 and an RX Phi terminal 252, and transmits frames to a connected communication device from the TX Phi terminal 251, and receives frames from the connected communication device at the RX Phi terminal 252. The TX Phi terminal 251 is connected to the transmit terminal TX221, and the RX Phi terminal 252 is connected to the receive terminal RX222.

[0085] The Phi 250 also detects the link between the RX Phi terminal 252 and the communication device to which it is connected.

[0086] The detection unit 25 detects an abnormality related to the connection of the third input / output port 21 and an abnormality related to the connection of the fourth input / output port 22. More specifically, the detection unit 25 detects an abnormality related to the connection of the third input / output port 21 when Phi 230 changes from a state in which it detects a link between the RX Phi terminal 232 and its connected communication device to a state in which it does not detect the link, and detects an abnormality related to the connection of the fourth input / output port 22 when Phi 250 changes from a state in which it detects a link between the RX Phi terminal 252 and its connected communication device to a state in which it does not detect the link.

[0087] Furthermore, the detection unit 25 detects recovery from an abnormality related to the connection of the third input / output port 21 and recovery from an abnormality related to the connection of the fourth input / output port 22. More specifically, the detection unit 25 detects recovery from an abnormality related to the connection of the third input / output port 21 when Phi 230 changes from a state in which it has not detected a link between the RX Phi terminal 232 and its connected communication device to a state in which it has detected the link, and detects recovery from an abnormality related to the connection of the fourth input / output port 22 when Phi 250 changes from a state in which it has not detected a link between the RX Phi terminal 252 and its connected communication device to a state in which it has detected the link.

[0088] The detection unit 25 may be realized, for example, by a processor 201 included in the slave 20 executing a program stored in a memory 202 included in the slave 20.

[0089] The slave transmission control unit 23 operates in either the first slave operation mode or the second slave operation mode. In the initial state, the slave transmission control unit 23 operates in the first slave operation mode.

[0090] In the first slave operation mode, when one of the third input / output port 21 and the fourth input / output port 22 receives a normal frame, the slave transmission control unit 23 transmits the normal frame from the other of the third input / output port 21 and the fourth input / output port 22. More specifically, in the first slave operation mode, the slave transmission control unit 23 controls Phi 230 and Phi 250 to transmit the normal frame from the TX Phi terminal 251 when the RX Phi terminal 232 receives the normal frame, and to transmit the normal frame from the TX Phi terminal 231 when the RX Phi terminal 252 receives the normal frame. Note that the normal frame transmitted by the other input / output port is a normal frame obtained by controlling Phi 230 and Phi 250 for the normal frame received by the one input / output port. For example, the received normal frame may be directly converted into the transmitted normal frame by controlling Phi 230 and Phi 250, i.e., the normal frame may be passed through. Furthermore, as a normal frame, for example, the received normal frame may be converted into the normal frame to be transmitted under the control of Phi 230 and Phi 250.

[0091] In the second slave operation mode, when a normal frame is received by one of the third input / output port 21 and the fourth input / output port 22, the slave transmission control unit 23 transmits the normal frame from that one input / output port. More specifically, in the second slave operation mode, the slave transmission control unit 23 controls Phi 230 and Phi 250 to transmit the normal frame from the TX Phi terminal 231 when the RX Phi terminal 232 receives the normal frame, and to transmit the normal frame from the TX Phi terminal 251 when the RX Phi terminal 252 receives the normal frame.

[0092] When operating in the first slave operation mode, the slave transmission control unit 23 switches the operation mode from the first slave operation mode to the second slave operation mode when the detection unit 25 detects an abnormality in the connection of the third input / output port 21 or the fourth input / output port 22. At the same time, the slave transmission control unit 23 attempts to transmit a disconnection node notification frame indicating that a change in the connection status has been detected from the third input / output port 21 and the fourth input / output port 22. More specifically, the slave transmission control unit 23 controls Phi 230 and Phi 250 to attempt to transmit a disconnection node notification frame from the TX Phi terminal 231 and to attempt to transmit a disconnection node notification frame from the TX Phi terminal 251.

[0093] At this time, the slave transmission control unit 23 causes the disconnection node notification frame that it attempts to transmit to include the MAC ID of the slave 20 that includes the slave transmission control unit 23. Also, at this time, when the detection unit 25 detects an abnormality in the connection of one of the third input / output port 21 and the fourth input / output port 22, the slave transmission control unit 23 attempts to transmit a disconnection node notification frame that includes a node count value that indicates 0 from the one input / output port, and attempts to transmit a disconnection node notification frame that includes a node count value that indicates 1 from the other input / output port.

[0094] When operating in the second slave operation mode, if the detection unit 25 detects recovery from an abnormality related to the connection of the third input / output port 21 or recovery from an abnormality related to the connection of the fourth input / output port 22, the slave transmission control unit 23 switches the operation mode from the second slave operation mode to the first slave operation mode and transmits a disconnection node notification frame from the third input / output port 21 and the fourth input / output port 22. More specifically, the slave transmission control unit 23 controls Phi 230 and Phi 250 to transmit a disconnection node notification frame from the TX Phi terminal 231 and transmit a disconnection node notification frame from the TX Phi terminal 251.

[0095] At this time, the slave transmission control unit 23 includes the MAC ID of the slave 20 including the slave transmission control unit 23 in the disconnection node notification frame to be transmitted. Also, at this time, when the detection unit 25 detects recovery from an abnormality related to the connection of one of the third input / output port 21 and the fourth input / output port 22, the slave transmission control unit 23 transmits a disconnection node notification frame including a node count value indicating 0 from the one input / output port, and transmits a disconnection node notification frame including a node count value indicating 1 from the other input / output port.

[0096] When one of the third input / output port 21 and the fourth input / output port 22 receives a line-disconnection node notification frame, the slave transmission control unit 23 transmits the line-disconnection node notification frame from the other input / output port. More specifically, the slave transmission control unit 23 controls Phi 230 and Phi 250 so that when the RX Phi terminal 232 receives the line-disconnection node notification frame, the slave transmission control unit 23 causes the TX Phi terminal 251 to transmit the line-disconnection node notification frame, and when the RX Phi terminal 252 receives the line-disconnection node notification frame, the slave transmission control unit 23 causes the TX Phi terminal 231 to transmit the line-disconnection node notification frame. The line-disconnection node notification frame transmitted by the other input / output port is obtained by controlling Phi 230 and Phi 250 in response to the line-disconnection node notification frame received by the one input / output port. As the disconnection node notification frame, for example, the received disconnection node notification frame may be directly used as the disconnection node notification frame to be transmitted, i.e., the disconnection node notification frame may be passed through, under the control of Phi 230 and Phi 250. Also, as the disconnection node notification frame, for example, the received disconnection node notification frame may be converted and used as the disconnection node notification frame to be transmitted under the control of Phi 230 and Phi 250.

[0097] At this time, the slave transmission control unit 23 transmits from one input / output port a disconnection node notification frame including a node count value obtained by adding 1 to the node count value included in the disconnection node notification frame received by the other input / output port.

[0098] When the slave transmission control unit 23 is operating in the first slave operation mode, if the third input / output port 21 or the fourth input / output port 22 receives a disconnection node notification frame including a node count value indicating 0, the slave transmission control unit 23 switches the operation mode from the first slave operation mode to the second slave operation mode.

[0099] When the slave transmission control unit 23 is operating in the second slave operation mode, if the third input / output port 21 or the fourth input / output port 22 receives a disconnection node notification frame including a node count value including 0, the slave transmission control unit 23 switches the operation mode from the second slave operation mode to the first slave operation mode.

[0100] The slave transmission control unit 23 may be realized, for example, by a processor 201 included in the slave 20 executing a program stored in a memory 202 included in the slave 20.

[0101] The synchronization timing calculation unit 24 calculates a synchronization timing signal indicating the synchronization timing at which all of the multiple slaves 20 operate in synchronization, based on the timing at which the third input / output port 21 or the fourth input / output port 22 receives the normal frame.

[0102] 4 is a schematic diagram showing a transmission path of a normal frame (hereinafter also referred to as a "main transmission path") when the controller transmission control unit 13 operates in the first controller operation mode and the slave transmission control units 23 of the first slave 20A, the second slave 20B, and the third slave 20C operate in the first slave operation mode. This main transmission path is the transmission path of a normal frame when the controller transmission control unit 13 and the slave transmission control unit 23 are in the initial state.

[0103] In FIG. 4, the main transmission path is the path indicated by the solid arrow.

[0104] As shown in FIG. 4, the main transmission path is a transmission path that starts from the controller 10, passes through the first slave 20A, the second slave 20B, and the third slave 20C in this order, and returns to the controller 10 again.

[0105] 5 is a timing chart showing an example of the transmission and reception timing of the normal frame 50 in the controller 10 and each slave 20 when the transmission path of the normal frame 50 is the main transmission path, and the operation timing of the synchronization timing signal XSYNC calculated by the synchronization timing calculation unit 24 of each slave 20. In FIG. 5, the horizontal axis represents time t.

[0106] As shown in FIG. 5, the synchronization timing calculation unit 24 of each slave 20 calculates a synchronization timing signal XSYNC that operates in synchronization with each other.

[0107] Here, the synchronization timing calculation unit 24 stores in advance the number of slaves 20 (here, 3) and the connection order from the controller 10 in the main transmission path (here, 1 for the first slave 20A, 2 for the second slave 20B, and 3 for the third slave 20C), and calculates the pulse timing T of the synchronization timing signal XSYNC using (Equation 1).

[0108] T= Normal frame reception completion time + (number of all slaves 20 - connection order in the transmission path) x fixed delay value ... (Formula 1) Here, the "connection order in the transmission path" in (Equation 1) is the connection order from the controller 10 in the main transmission path, which is stored in advance by the synchronization timing calculation unit 24.

[0109] 6 is a schematic diagram showing a transmission path of a normal frame (hereinafter also referred to as a "first redundant transmission path") when the controller transmission control unit 13 operates in the second controller operation mode, the slave transmission control unit 23 of the first slave 20A operates in the first slave operation mode, and the slave transmission control units 23 of the second slave 20B and the third slave 20C operate in the second slave operation mode. Details will be described later, but this first redundant transmission path is a transmission path that is formed by changing from the main transmission path when, for example, the transmission path of a normal frame is the main transmission path and the detection unit 25 of the second slave 20B detects an abnormality in the connection of the third input / output port 21, or when the detection unit 25 of the third slave 20C detects an abnormality in the connection of the fourth input / output port 22.

[0110] In FIG. 6, the first redundant transmission path is the path indicated by the solid arrow.

[0111] 6, the first redundant transmission path consists of a first transmission path and a second transmission path. The first transmission path is a transmission path that starts from the controller 10, passes through the first slave 20A, the second slave 20B, and the first slave 20A, and then returns to the controller 10 again, i.e., a path that loops back at the second slave 20B. The second transmission path is a transmission path that starts from the controller 10, passes through the third slave 20C, and then returns to the controller 10 again, i.e., a path that loops back at the third slave 20C.

[0112] 6, the connection order of the first slave 20A and the second slave 20B from the controller 10 in the first redundant transmission path is not changed from the connection order in the main transmission path. On the other hand, the connection order of the third slave 20C from the controller 10 in the first redundant transmission path is changed from the connection order in the main transmission path (here, changed from 3 to 1).

[0113] 7 is a timing chart showing an example of the transmission and reception timing of the normal frame 50 in the controller 10 and each slave 20 when the transmission path of the normal frame 50 is the first redundant transmission path, and the operation timing of the synchronization timing signal XSYNC calculated by the synchronization timing calculation unit 24 of each slave 20. In FIG. 7, the horizontal axis represents time t.

[0114] In the first slave 20A and the second slave 20B, even if the transmission path is changed from the main transmission path to the first redundant transmission path, the "connection order in the transmission path" in (Equation 1) does not change. Therefore, even if the transmission path is changed from the main transmission path to the first redundant transmission path in the first slave 20A and the second slave 20B, the calculation method of the pulse timing T of the synchronization timing signal XSYNC does not change.

[0115] On the other hand, in the third slave 20C, when the transmission path is changed from the main transmission path to the first redundant transmission path, the "connection order on the transmission path" in (Equation 1) is changed.

[0116] In contrast, when the connection order in the transmission path is changed, the synchronization timing calculation unit 24 calculates the "connection order in the transmission path" based on the node count value included in the disconnection node notification frame. As a result, even if the "connection order in the transmission path" is changed, the synchronization timing calculation unit 24 does not change the pulse timing T of the synchronization timing signal XSYNC. In this way, the synchronization timing calculation unit 24 updates the calculation method for the pulse timing T of the synchronization timing signal XSYNC so that the pulse timing T of the synchronization timing signal XSYNC does not change even if the "connection order in the transmission path" is changed. Therefore, even if the transmission path in the third slave 20C is changed from the main transmission path to the first redundant transmission path, the pulse timing T of the synchronization timing signal XSYNC does not change. Note that the calculation of the "connection order in the transmission path" performed by the synchronization timing calculation unit 24 when the "connection order in the transmission path" is changed will be described later.

[0117] The synchronization timing calculation unit 24 may be realized, for example, by a processor 201 included in the slave 20 executing a program stored in a memory 202 included in the slave 20.

[0118] [1-2. Operation] The operation of the communication system 1 having the above configuration will be explained below using a specific example.

[0119] First, when the transmission path of a normal frame is the main transmission path, an operation (hereinafter also referred to as "first operation") performed by the communication system 1 when a cable disconnection abnormality occurs in the cable 30C, causing the cable 30 to be disconnected will be described. Note that the cable disconnection abnormality here refers not only to an abnormality in which the cable is disconnected, but also to an abnormality in which communication via the cable becomes impossible due to, for example, the cable coming off the connector.

[0120] Fig. 8 is a schematic diagram showing a state in which a cable disconnection abnormality occurs in the cable 30C, causing a disconnection of the cable 30. Fig. 9 is a sequence diagram of the first operation.

[0121] 9, when a cable breakage abnormality occurs in the cable 30C, in the third slave 20C, the Phi 250 no longer detects the link between the RX Phi terminal 252 and the TX Phi terminal 231 of the Phi 230 of the second slave 20B, which is its connection destination. Therefore, in the third slave 20C, the detection unit 25 of the third slave 20C detects an abnormality related to the connection of the fourth input / output port 22 (step S10A).

[0122] When the detection unit 25 of the third slave 20C detects an abnormality in the connection of the fourth input / output port 22, the slave transmission control unit 23 of the third slave 20C switches the operation mode from the first slave operation mode to the second slave operation mode (step S20A).

[0123] Then, the slave transmission control unit 23 of the third slave 20C attempts to transmit, from the third input / output port 21 and the fourth input / output port 22, a disconnection node notification frame indicating that a change in the connection state has been detected (step S30A).

[0124] At this time, the slave transmission control unit 23 of the third slave 20C causes the disconnection node notification frame that it attempts to transmit to include the MAC ID of the third slave 20C, which includes the slave transmission control unit 23. Furthermore, the slave transmission control unit 23 of the third slave 20C attempts to transmit a disconnection node notification frame that includes a node count value indicating 1 from the third input / output port 21, and attempts to transmit a disconnection node notification frame that includes a node count value indicating 0 from the fourth input / output port 22.

[0125] As described above, a cable disconnection abnormality has occurred in the cable 30C. Therefore, the attempt to transmit a disconnected node notification frame from the fourth I / O port 22 fails. On the other hand, the attempt to transmit a disconnected node notification frame from the third I / O port 21 is successful. That is, the slave transmission control unit 23 of the third slave 20C transmits a disconnected node notification frame from the third I / O port 21 (step S40A).

[0126] Here, when the detection unit 25 of the third slave 20C detects an abnormality related to the connection of the fourth input / output port 22, the transmission path of the normal frame is the main transmission path. Also, as will be described later, when a cable disconnection abnormality occurs in the cable 30C, the transmission path of the normal frame is changed from the main transmission path to the first redundant transmission path. Therefore, in the third slave 20C, the connection order from the controller 10 of the third slave 20C in the transmission path of the normal frame is changed (here, from 3 to 1).

[0127] The synchronization timing calculation unit 24 calculates the "connection order on the transmission path" in (Equation 1) so that the pulse timing T of the synchronization timing signal XSYNC will not be changed even if the transmission path of the normal frame is changed from the main transmission path to the first redundant transmission path. More specifically, the synchronization timing calculation unit 24 calculates the "connection order on the transmission path" in (Equation 1) by subtracting the connection order from the controller 10 (the connection order from the controller 10 on the main transmission path that is stored in advance (here, 3)) at the time when the detection unit 25 detected the connection abnormality from the controller 10 (here, the connection order from the controller 10 on the main transmission path that is stored in advance (here, 3)), and adding 1 (here, 3 - 3 + 1 = 1),

[0128] In this way, the synchronization timing calculation unit 24 updates the calculation method for the pulse timing T of the synchronization timing signal XSYNC so that the pulse timing T of the synchronization timing signal XSYNC does not change even if the "connection order in the transmission path" is changed (step S50). In other words, when the detection unit 25 detects an abnormality in the connection of the input / output port on the side receiving the normal frame, the synchronization timing calculation unit 24 updates the calculation method for calculating the synchronization timing signal XSYNC so that the synchronization timing at which all of the multiple slaves 20 operate in synchronization does not change when an input / output port other than the detected input / output port receives a normal frame from the next time onwards.

[0129] On the other hand, if a cable breakage abnormality occurs in the cable 30C, in the second slave 20B, the Phi 230 no longer detects the link between the RX Phi terminal 232 and the TX Phi terminal 251 of the Phi 250 of the third slave 20C, which is its connection destination. Therefore, in the second slave 20B, the detection unit 25 of the second slave 20B detects an abnormality related to the connection of the third input / output port 21 (step S10B).

[0130] When the detection unit 25 of the second slave 20B detects an abnormality in the connection of the third input / output port 21, the slave transmission control unit 23 of the second slave 20B switches the operation mode from the first slave operation mode to the second slave operation mode (step S20B).

[0131] Then, the slave transmission control unit 23 of the second slave 20B attempts to transmit a disconnection node notification frame from the third input / output port 21 and the fourth input / output port 22 (step S30B).

[0132] At this time, the slave transmission control unit 23 of the second slave 20B causes the disconnection node notification frame that it attempts to transmit to include the MAC ID of the second slave 20B, which includes the slave transmission control unit 23. Furthermore, the slave transmission control unit 23 of the second slave 20B attempts to transmit a disconnection node notification frame that includes a node count value indicating 0 from the third input / output port 21, and attempts to transmit a disconnection node notification frame that includes a node count value indicating 1 from the fourth input / output port 22.

[0133] As described above, a cable disconnection abnormality has occurred in the cable 30C. Therefore, the attempt to transmit a disconnected node notification frame from the third I / O port 21 fails. On the other hand, the attempt to transmit a disconnected node notification frame from the fourth I / O port 22 is successful. That is, the slave transmission control unit 23 of the second slave 20B transmits a disconnected node notification frame from the fourth I / O port 22 (step S40B).

[0134] Here, when the detection unit 25 of the second slave 20B detects an abnormality in the connection of the third input / output port 21, the transmission path of the normal frame is the main transmission path. Also, as will be described later, when a cable breakage abnormality occurs in the cable 30C, the transmission path of the normal frame is changed from the main transmission path to the first redundant transmission path. Therefore, in the second slave 20B, the connection order from the controller 10 of the third slave 20C in the transmission path of the normal frame is not changed. Therefore, the synchronization timing calculation unit 24 of the second slave 20B does not update the calculation method of the pulse timing T of the synchronization timing signal XSYNC.

[0135] In the processing of step S40B, when the slave transmission control unit 23 of the second slave 20B transmits a disconnection node notification frame from the fourth input / output port 22, the third input / output port 21 of the first slave 20A receives the disconnection node notification frame.

[0136] When the third input / output port 21 of the first slave 20A receives the disconnection node notification frame, the slave transmission control unit 23 of the first slave 20A transmits the disconnection node notification frame from the fourth input / output port 22, which includes a node count value obtained by adding 1 to the node count value (here, 1) included in the disconnection node notification frame (here, 1+1=2) (step S40C).

[0137] In the processing of step S40A, when the slave transmission control unit 23 of the third slave 20C transmits a disconnected node notification frame (hereinafter also referred to as the "first disconnected node notification frame") from the third input / output port 21, the second input / output port 12 receives the first disconnected node notification frame.

[0138] In the processing of step S40C, when the slave transmission control unit 23 of the first slave 20A transmits a disconnection node notification frame (hereinafter also referred to as the "second disconnection node notification frame") from the fourth input / output port 22, the first input / output port 11 receives the second disconnection node notification frame.

[0139] When the second input / output port 12 receives the first disconnection node notification frame and the first input / output port 11 receives the second disconnection node notification frame, the abnormality type determination unit 15 compares the MACID included in the first disconnection node notification frame (here, the MACID of the third slave 20C) with the MACID included in the second disconnection node notification frame (here, First slave 20A Based on the MACID, it is determined that the abnormality that has occurred in the communication system 1 is a cable disconnection abnormality (step S60).

[0140] That is, when the first input / output port 11 and the second input / output port 12 receive disconnected node notification frames within a predetermined time, and the MACIDs contained in the disconnected node notification frames are different from each other, the abnormality type determination unit 15 determines that the abnormality occurring in the communication system 1 is a cable disconnection abnormality.

[0141] Furthermore, the abnormality type determination unit 15 determines that the location of the cable disconnection abnormality is between the third slave 20C and the second slave 20B based on the MACID included in the first disconnection node notification frame (here, the MACID of the third slave 20C) and the MACID included in the second disconnection node notification frame (here, the MACID of the second slave 20B) (step S70).

[0142] In other words, when the first input / output port 11 and the second input / output port 12 receive disconnection node notification frames within a predetermined time, and the MACIDs contained in the disconnection node notification frames are different from each other, the abnormality type determination unit 15 determines that the location of the abnormality that occurred in the communication system 1 is between the slaves 20 of those MACIDs.

[0143] When the abnormality type determination unit 15 determines the location where the abnormality has occurred, the controller transmission control unit 13 switches the operation mode from the first controller operation mode to the second controller operation mode (step S80).

[0144] The first operation performed by the communication system 1 changes the operation mode of the controller transmission control unit 13 from the first controller operation mode to the second controller operation mode. Also, the first operation performed by the communication system 1 changes the operation mode of the slave transmission control unit 23 of the third slave 20C from the first slave operation mode to the second slave operation mode. Also, the first operation performed by the communication system 1 changes the operation mode of the slave transmission control unit 23 of the second slave 20B from the first slave operation mode to the second slave operation mode. As a result, the transmission path of normal frames is changed from the main communication path (see FIG. 4) to the first redundant transmission path (see FIG. 6).

[0145] In this way, when the transmission path of a normal frame is the main transmission path and a cable breakage abnormality occurs in the cable 30, the communication system 1 changes the transmission path to a transmission path that does not use the cable 30 in which the cable breakage abnormality occurred, and transmits the normal frame to each slave 20.

[0146] Next, we will explain the operation (hereinafter also referred to as the "second operation") performed by the communication system 1 when a phi terminal abnormality occurs in which the TX phi terminal 231 of the second slave 20B stops functioning when the transmission path of a normal frame is the main transmission path.

[0147] Fig. 10 is a schematic diagram showing a state in which a phi terminal abnormality occurs in the TX phi terminal 231 of the second slave 20B, causing the TX phi terminal 231 to stop functioning. Fig. 11 is a sequence diagram of the second operation. Note that here, the phi terminal abnormality that causes the TX phi terminal to stop functioning refers to an abnormality that causes the TX phi terminal to stop functioning due to, for example, a phi failure or a problem in the connection path of the TX phi terminal.

[0148] 11, when a Phi terminal abnormality occurs in the TX Phi terminal 231 of the second slave 20B, causing the TX Phi terminal 231 of the second slave 20B to stop functioning, the Phi 250 in the third slave 20C no longer detects the link between the RX Phi terminal 252 and the TX Phi terminal 231 of the Phi 230 of the second slave 20B, which is its connection destination. Therefore, in the third slave 20C, the detection unit 25 of the third slave 20C detects an abnormality related to the connection of the fourth input / output port 22 (step S110).

[0149] When the detection unit 25 of the third slave 20C detects an abnormality in the connection of the fourth input / output port 22, the slave transmission control unit 23 of the third slave 20C switches the operation mode from the first slave operation mode to the second slave operation mode (step S120).

[0150] Then, the slave transmission control unit 23 of the third slave 20C attempts to transmit a disconnection node notification frame from the third input / output port 21 and the fourth input / output port 22 (step S130).

[0151] At this time, the slave transmission control unit 23 of the third slave 20C causes the disconnection node notification frame that it attempts to transmit to include the MAC ID of the third slave 20C, which includes the slave transmission control unit 23. Furthermore, the slave transmission control unit 23 of the third slave 20C attempts to transmit a disconnection node notification frame that includes a node count value indicating 1 from the third input / output port 21, and attempts to transmit a disconnection node notification frame that includes a node count value indicating 0 from the fourth input / output port 22.

[0152] As described above, a phi terminal abnormality has occurred in the TX phi terminal 231 of the second slave 20B, causing the TX phi terminal 231 of the second slave 20B to stop functioning. However, signal transmission from the TX phi terminal 251 of the third slave 20C to the RX phi terminal 232 of the second slave 20B is possible. Therefore, the attempt to transmit a disconnection-node notification frame from the fourth input / output port 22 is successful. That is, the slave transmission control unit 23 of the third slave 20C transmits a disconnection-node notification frame from the fourth input / output port 22 (step S140B). Meanwhile, the attempt to transmit a disconnection-node notification frame from the third input / output port 21 is also successful. That is, the slave transmission control unit 23 of the third slave 20C transmits a disconnection-node notification frame from the third input / output port 21 (step S140A).

[0153] Here, when the detection unit 25 of the third slave 20C detects an abnormality in the connection of the fourth input / output port 22, the transmission path of the normal frame is the main transmission path. Also, as will be described later, a Phi terminal abnormality occurs in the TX Phi terminal 231 of the second slave 20B, causing the TX Phi terminal 231 of the second slave 20B to stop functioning, and the transmission path of the normal frame is changed from the main transmission path to the first redundant transmission path. Therefore, in the third slave 20C, the connection order from the controller 10 of the third slave 20C in the transmission path of the normal frame is changed (here, from 3 to 1).

[0154] Therefore, the synchronization timing calculation unit 24 updates the calculation method for the pulse timing T of the synchronization timing signal XSYNC so that the pulse timing T of the synchronization timing signal XSYNC does not change even if the "connection order in the transmission path" is changed (step S150).

[0155] On the other hand, even if a Phi terminal abnormality occurs in the TX Phi terminal 231 of the second slave 20B, causing the TX Phi terminal 231 of the second slave 20B to stop functioning, the Phi 230 in the second slave 20B detects a link between the RX Phi terminal 232 and the TX Phi terminal 251 of the Phi 250 of the third slave 20C, which is its connection destination. Therefore, in the second slave 20B, the detection unit 25 of the second slave 20B does not detect an abnormality related to the connection of the third input / output port 21.

[0156] In the processing of step S140B, when the slave transmission control unit 23 of the third slave 20C transmits a disconnection node notification frame from the fourth input / output port 22, the third input / output port 21 of the second slave 20B receives the disconnection node notification frame.

[0157] When the third input / output port 21 of the second slave 20B receives the disconnection node notification frame, the slave transmission control unit 23 of the second slave 20B transmits the disconnection node notification frame from the fourth input / output port 22, which includes a node count value obtained by adding 1 to the node count value (here, 0) included in the disconnection node notification frame (here, 0+1=1) (step S140C).

[0158] Here, since the slave transmission control unit 23 of the second slave 20B has received a disconnection node notification frame including a node count value indicating 0, it switches the operation mode from the first slave operation mode to the second slave operation mode (step S160).

[0159] In the processing of step S140C, when the slave transmission control unit 23 of the second slave 20B transmits a disconnection node notification frame at the fourth input / output port 22, the third input / output port 21 of the first slave 20A receives the disconnection node notification frame.

[0160] When the third input / output port 21 of the first slave 20A receives the disconnection node notification frame, the slave transmission control unit 23 of the first slave 20A transmits the disconnection node notification frame from the fourth input / output port 22, which includes a node count value obtained by adding 1 to the node count value (here, 1) included in the disconnection node notification frame (here, 1+1=2) (step S140D).

[0161] In the processing of step S140A, when the slave transmission control unit 23 of the third slave 20C transmits a disconnected node notification frame (hereinafter also referred to as the "third disconnected node notification frame") from the third input / output port 21, the second input / output port 12 receives the third disconnected node notification frame.

[0162] In the processing of step S140D, when the slave transmission control unit 23 of the first slave 20A transmits a disconnected node notification frame (hereinafter also referred to as the "fourth disconnected node notification frame") from the fourth input / output port 22, the first input / output port 11 receives the fourth disconnected node notification frame.

[0163] When the second input / output port 12 receives the third line-disconnection node notification frame and the first input / output port 11 receives the fourth line-disconnection node notification frame, the abnormality type determination unit 15 compares the MACID included in the third line-disconnection node notification frame (here, the MACID of the third slave 20C) with the MACID included in the fourth line-disconnection node notification frame (here, First slave 20A Based on the MACID of the Phi terminal, it is determined that the abnormality that has occurred in the communication system 1 is a Phi terminal abnormality (step S170).

[0164] That is, when the first input / output port 11 and the second input / output port 12 receive disconnected node notification frames within a predetermined time, and the MACIDs contained in the disconnected node notification frames are equal, the abnormality type determination unit 15 determines that the abnormality occurring in the communication system 1 is a Phi terminal abnormality.

[0165] When the abnormality type determination unit 15 determines that the abnormality occurring in the communication system 1 is a Phi terminal abnormality, the abnormality position determination unit 14 determines that the location where the Phi terminal abnormality occurred is between the third slave 20C and the second slave 20B based on the node count values ​​contained in the third disconnection node notification frame and the fourth disconnection node notification frame (step S180).

[0166] That is, the abnormality position determination unit 14 identifies the two slaves 20 that transmitted the disconnection node notification frames containing node count values ​​indicating 1 (here, the third slave 20C and the second slave 20B) from the node count value (here, 1) included in the third disconnection node notification frame and the node count value (here, 2) included in the fourth disconnection node notification frame. Then, the abnormality position determination unit 14 determines that the location where the Phi terminal abnormality occurred is between the two identified slaves 20 (here, between the third slave 20C and the second slave 20B).

[0167] The abnormality position determination unit 14 may, for example, store the connection order of the slaves 20 in advance, and identify the two slaves 20 that sent disconnection note notification frames indicating a node count value of 1 from the stored connection order of the slaves 20 and the node count value.

[0168] When the abnormality position determination unit 14 determines the position where the abnormality has occurred, the controller transmission control unit 13 switches the operation mode from the first controller operation mode to the second controller operation mode (step S190).

[0169] The second operation performed by the communication system 1 changes the operation mode of the controller transmission control unit 13 from the first controller operation mode to the second controller operation mode. Furthermore, the second operation performed by the communication system 1 changes the operation mode of the slave transmission control unit 23 of the third slave 20C from the first slave operation mode to the second slave operation mode. Furthermore, the second operation performed by the communication system 1 changes the operation mode of the slave transmission control unit 23 of the second slave 20B from the first slave operation mode to the second slave operation mode. As a result, the transmission path of normal frames is changed from the main communication path (see FIG. 4) to the first redundant transmission path (see FIG. 6).

[0170] In this way, when the transmission path of a normal frame is the main transmission path and a phi terminal abnormality occurs that causes the TX phi terminal to stop functioning, the communication system 1 changes the transmission path to a transmission path that does not use the phi where the phi terminal abnormality occurred, and transmits the normal frame to each slave 20.

[0171] Next, we will explain the operation (hereinafter also referred to as the "third operation") performed by the communication system 1 when a phi terminal abnormality occurs in which the RX phi terminal 252 of the second slave 20B stops functioning when the transmission path of a normal frame is the main transmission path.

[0172] Fig. 12 is a schematic diagram showing a state in which a phi terminal abnormality occurs in the RX phi terminal 252 of the second slave 20B, causing the RX phi terminal 252 to stop functioning. Fig. 13 is a sequence diagram of the third operation. Note that here, the phi terminal abnormality that causes the RX phi terminal to stop functioning refers to an abnormality that causes the RX phi terminal to stop functioning due to, for example, a phi failure or a problem in the connection path of the RX phi terminal.

[0173] 13, when a Phi terminal abnormality occurs in the RX Phi terminal 252 of the second slave 20B, causing the RX Phi terminal 252 of the second slave 20B to stop functioning, the Phi 250 in the second slave 20B no longer detects the link between the RX Phi terminal 252 and the TX Phi terminal 231 of the Phi 230 in the first slave 20A, to which it is connected. Therefore, in the second slave 20B, the detection unit 25 of the second slave 20B detects an abnormality related to the connection of the fourth input / output port 22 (step S210).

[0174] When the detection unit 25 of the second slave 20B detects an abnormality in the connection of the fourth input / output port 22, the slave transmission control unit 23 of the second slave 20B switches the operation mode from the first slave operation mode to the second slave operation mode (step S220).

[0175] Then, the slave transmission control unit 23 of the second slave 20B attempts to transmit a disconnection node notification frame from the third input / output port 21 and the fourth input / output port 22 (step S230).

[0176] At this time, the slave transmission control unit 23 of the second slave 20B causes the disconnection node notification frame that it attempts to transmit to include the MAC ID of the second slave 20B, which includes the slave transmission control unit 23. Furthermore, the slave transmission control unit 23 of the second slave 20B attempts to transmit a disconnection node notification frame that includes a node count value indicating 1 from the third input / output port 21, and attempts to transmit a disconnection node notification frame that includes a node count value indicating 0 from the fourth input / output port 22.

[0177] As described above, a phi terminal abnormality has occurred in the RX phi terminal 252 of the second slave 20B, causing the RX phi terminal 252 of the second slave 20B to stop functioning. However, signal transmission from the TX phi terminal 251 of the second slave 20B to the RX phi terminal 232 of the first slave 20A is possible. Therefore, the attempt to transmit a disconnection-node notification frame from the fourth input / output port 22 is successful. That is, the slave transmission control unit 23 of the second slave 20B transmits the disconnection-node notification frame from the fourth input / output port 22 (step S240B). Meanwhile, the attempt to transmit a disconnection-node notification frame from the third input / output port 21 is also successful. That is, the slave transmission control unit 23 of the second slave 20B transmits the disconnection-node notification frame from the third input / output port 21 (step S240A).

[0178] Here, when the detection unit 25 of the second slave 20B detects an abnormality in the connection of the fourth input / output port 22, the transmission path of the normal frame is the main transmission path. Also, as will be described later, a Phi terminal abnormality occurs in the RX Phi terminal 252 of the second slave 20B, causing the RX Phi terminal 252 of the second slave 20B to stop functioning, and the transmission path of the normal frame is changed from the main transmission path to a second redundant transmission path (described later). Therefore, in the second slave 20B, the connection order from the controller 10 of the second slave 20B in the transmission path of the normal frame is changed. Here, it appears as if the change from 2 to 2 has not occurred, but in this example, the connection order before the change and the connection order after the change happen to be the same, so it simply appears as if the change has not occurred.

[0179] 14 is a schematic diagram showing a second redundant transmission path. The second redundant transmission path is a transmission path for normal frames when the controller transmission control unit 13 operates in the second controller operation mode, the slave transmission control units 23 of the first slave 20A and the second slave 20B operate in the second slave operation mode, and the slave transmission control unit 23 of the third slave 20C operates in the first slave operation mode.

[0180] In FIG. 14, the second redundant transmission path is the path indicated by the solid arrow.

[0181] 14, the second redundant transmission path is made up of a first transmission path and a second transmission path. The first transmission path is a first transmission path that starts from the controller 10, passes through the first slave 20A, and returns to the controller 10 again, i.e., a path that loops back at the first slave 20A. The second transmission path is a transmission path that starts from the controller 10, passes through the third slave 20C, the second slave 20B, and the third slave 20C, and returns to the controller 10 again, i.e., a path that loops back at the second slave 20B. Route and The transmission path consists of:

[0182] Returning to FIG. 13 again, the description of the third operation will be continued.

[0183] In the second slave 20B, the synchronization timing calculation unit 24 calculates the "connection order on the transmission path" in (Equation 1) so that the pulse timing T of the synchronization timing signal XSYNC is not changed even if the transmission path of the normal frame is changed from the main transmission path to the second redundant transmission path. More specifically, the synchronization timing calculation unit 24 calculates the "connection order on the transmission path" in (Equation 1) by subtracting the connection order from the controller 10 (the connection order from the controller 10 on the main transmission path that is stored in advance (here, 2)) at the time when the detection unit 25 detected the abnormality related to the connection from the controller 10 (here, 3)) from the number of slaves 20 stored in advance (here, 3), and adding 1 to the result (here, 3-2+1=2).

[0184] In this way, the synchronization timing calculation unit 24 updates the calculation method for the pulse timing T of the synchronization timing signal XSYNC so that the pulse timing T of the synchronization timing signal XSYNC does not change even if the "connection order in the transmission path" is changed (step S250).

[0185] In the processing of step S240A, when the slave transmission control unit 23 of the second slave 20B transmits a disconnection node notification frame from the third input / output port 21, the fourth input / output port 22 of the third slave 20C receives the disconnection node notification frame.

[0186] When the fourth input / output port 22 of the third slave 20C receives the disconnection node notification frame, the slave transmission control unit 23 of the third slave 20C transmits the disconnection node notification frame from the third input / output port 21, which includes a node count value obtained by adding 1 to the node count value (here, 1) included in the disconnection node notification frame (here, 1+1=2) (step S240C).

[0187] As described above, a Phi terminal abnormality occurs in the RX Phi terminal 252 of the second slave 20B, causing the RX Phi terminal 252 of the second slave 20B to stop functioning, and the transmission path of normal frames is changed from the main transmission path to the second redundant transmission path. As a result, in the third slave 20C, the connection order from the controller 10 of the third slave 20C in the transmission path of normal frames is changed (here, from 3 to 1).

[0188] In the third slave 20C, the synchronization timing calculation unit 24 calculates the "connection order on the transmission path" in (Equation 1) so that the pulse timing T of the synchronization timing signal XSYNC is not changed even if the transmission path of a normal frame is changed from the main transmission path to the second redundant transmission path. More specifically, the synchronization timing calculation unit 24 calculates the "connection order on the transmission path" in (Equation 1) by subtracting the connection order from the controller 10 (the connection order from the controller 10 on the main transmission path, which is stored in advance, (here, 3)) at the time when the detection unit 25 detected the abnormality in the connection from the controller 10 (here, 3)) from the number of slaves 20 stored in advance, and then adding 1 (here, 3 - 3 + 1 = 1),

[0189] In this way, the synchronization timing calculation unit 24 updates the calculation method for the pulse timing T of the synchronization timing signal XSYNC so that the pulse timing T of the synchronization timing signal XSYNC does not change even if the "connection order in the transmission path" is changed (step S270). In other words, when the synchronization timing calculation unit 24 receives a disconnection node notification frame at the input / output port that receives the normal frame (here, the fourth input / output port 22), it updates the calculation method for calculating the synchronization timing signal XSYNC so that the synchronization timing at which all of the multiple slaves 20 operate in synchronization does not change when an input / output port other than the received input / output port receives a normal frame from the next time onwards.

[0190] On the other hand, even if a Phi terminal abnormality occurs in the RX Phi terminal 252 of the second slave 20B, causing the RX Phi terminal 252 of the second slave 20B to stop functioning, in the first slave 20A, Phi 230 detects a link between the RX Phi terminal 232 and the TX Phi terminal 251 of Phi 250 of the second slave 20B, which is its connection destination. Therefore, in the first slave 20A, the detection unit 25 of the first slave 20A does not detect an abnormality related to the connection of the third input / output port 21.

[0191] In the processing of step S240B, when the slave transmission control unit 23 of the second slave 20B transmits a disconnection node notification frame from the fourth input / output port 22, the third input / output port 21 of the first slave 20A receives the disconnection node notification frame.

[0192] When the third input / output port 21 of the first slave 20A receives the disconnection node notification frame, the slave transmission control unit 23 of the first slave 20A transmits the disconnection node notification frame from the fourth input / output port 22, which includes a node count value obtained by adding 1 to the node count value (here, 0) included in the disconnection node notification frame (here, 0+1=1) (step S240D).

[0193] Here, since the slave transmission control unit 23 of the first slave 20A has received the disconnection node notification frame including the node count value indicating 0, it switches the operation mode from the first slave operation mode to the second slave operation mode (step S260).

[0194] In the processing of step S240C, when the slave transmission control unit 23 of the third slave 20C transmits a disconnected node notification frame (hereinafter also referred to as the "fifth disconnected node notification frame") from the third input / output port 21, the second input / output port 12 receives the fifth disconnected node notification frame.

[0195] In the processing of step S240D, when the slave transmission control unit 23 of the first slave 20A transmits a disconnected node notification frame (hereinafter also referred to as the "sixth disconnected node notification frame") from the fourth input / output port 22, the first input / output port 11 receives the sixth disconnected node notification frame.

[0196] When the second input / output port 12 receives the fifth disconnection node notification frame and the first input / output port 11 receives the sixth disconnection node notification frame, the abnormality type determination unit 15 determines whether the MACID (here, Third slave 20C MACID) and the MACID included in the sixth disconnection node notification frame (here, First slave 20A Based on the MACID of the Phi terminal, it is determined that the abnormality that has occurred in the communication system 1 is a Phi terminal abnormality (step S280).

[0197] When the abnormality type determination unit 15 determines that the abnormality occurring in the communication system 1 is a Phi terminal abnormality, the abnormality location determination unit 14 determines that the location where the Phi terminal abnormality occurred is between the second slave 20B and the first slave 20A based on the node count values ​​contained in the fifth disconnection node notification frame and the sixth disconnection node notification frame (step S290).

[0198] That is, the abnormality position determination unit 14 identifies the two slaves 20 that transmitted the disconnection node notification frames containing node count values ​​indicating 1 (here, the second slave 20B and the first slave 20A) from the node count value (here, 2) included in the fifth disconnection node notification frame and the node count value (here, 1) included in the sixth disconnection node notification frame. Then, the abnormality position determination unit 14 determines that the location where the Phi terminal abnormality occurred is between the two identified slaves 20 (here, between the second slave 20B and the first slave 20A).

[0199] When the abnormality position determination unit 14 determines the position where the abnormality has occurred, the controller transmission control unit 13 switches the operation mode from the first controller operation mode to the second controller operation mode (step S300).

[0200] The third operation performed by the communication system 1 changes the operation mode of the controller transmission control unit 13 from the first controller operation mode to the second controller operation mode. Furthermore, the third operation performed by the communication system 1 changes the operation mode of the slave transmission control unit 23 of the second slave 20B from the first slave operation mode to the second slave operation mode. Furthermore, the third operation performed by the communication system 1 changes the operation mode of the slave transmission control unit 23 of the first slave 20A from the first slave operation mode to the second slave operation mode. As a result, the transmission path of normal frames is changed from the main communication path (see FIG. 4) to the second redundant transmission path (see FIG. 14).

[0201] In this way, when the transmission path of a normal frame is the main transmission path and a Phi terminal abnormality occurs in which the RX Phi terminal stops functioning, the communication system 1 changes the transmission path to a transmission path in which the Phi terminal abnormality has occurred and which does not use Phi, and transmits the normal frame to each slave 20.

[0202] Next, we will explain the operation (hereinafter also referred to as the "fourth operation") that the communication system 1 performs when the cable breakage abnormality in cable 30C is recovered in the case where the transmission path for normal frames is the first redundant transmission path due to the occurrence of a cable breakage abnormality in cable 30C.

[0203] Fig. 15 is a schematic diagram showing a state in which the cable 30C has recovered from a cable breakage abnormality. Fig. 16 is a sequence diagram of the fourth operation.

[0204] 16, when the cable breakage abnormality of the cable 30C is recovered, in the third slave 20C, the Phi 250 detects a link between the RX Phi terminal 252 and the TX Phi terminal 231 of the Phi 230 of the second slave 20B, which is its connection destination. Therefore, in the third slave 20C, the detection unit 25 of the third slave 20C detects the recovery of the abnormality related to the connection of the fourth input / output port 22 (step S310A).

[0205] When the detection unit 25 of the third slave 20C detects recovery from the abnormality related to the connection of the fourth input / output port 22, the slave transmission control unit 23 of the third slave 20C switches the operation mode from the second slave operation mode to the first slave operation mode (step S320A).

[0206] Then, the slave transmission control unit 23 of the third slave 20C transmits a disconnection node notification frame from the third input / output port 21 and the fourth input / output port 22 (step S340A).

[0207] At this time, the slave transmission control unit 23 of the third slave 20C includes the MAC ID of the third slave 20C including the slave transmission control unit 23 in the disconnection node notification frame to be transmitted.

[0208] Here, when the detection unit 25 of the third slave 20C detects recovery from the abnormality related to the connection of the fourth input / output port 22, the transmission path for normal frames is the first redundant transmission path. Also, as will be described later, as a result of recovery from the cable breakage abnormality of the cable 30C, the transmission path for normal frames is changed from the first redundant transmission path to the main transmission path. Therefore, in the third slave 20C, the connection order from the controller 10 of the third slave 20C in the transmission path for normal frames is changed (here, from 1 to 3).

[0209] The synchronization timing calculation unit 24 calculates the "connection order in the transmission path" in (Equation 1) so that the pulse timing T of the synchronization timing signal XSYNC does not change even if the transmission path of the normal frame is changed from the first redundant transmission path to the main transmission path. More specifically, the synchronization timing calculation unit 24 calculates the connection order from the controller 10 in the main transmission path, which is stored in advance (here, 3), as the "connection order in the transmission path" in (Equation 1).

[0210] In this way, the synchronization timing calculation unit 24 updates the calculation method for the pulse timing T of the synchronization timing signal XSYNC so that the pulse timing T of the synchronization timing signal XSYNC does not change even if the "connection order in the transmission path" is changed (step S350).

[0211] On the other hand, when the cable breakage abnormality of the cable 30C is recovered, in the second slave 20B, the Phi 230 detects a link between the RX Phi terminal 232 and the TX Phi terminal 251 of the Phi 250 of the third slave 20C, which is its connection destination. Therefore, in the second slave 20B, the detection unit 25 of the second slave 20B detects the recovery of the abnormality related to the connection of the third input / output port 21 (step S310B).

[0212] When the detection unit 25 of the second slave 20B detects recovery from the abnormality related to the connection of the third input / output port 21, the slave transmission control unit 23 of the second slave 20B switches the operation mode from the second slave operation mode to the first slave operation mode (step S320B).

[0213] Then, the slave transmission control unit 23 of the second slave 20B transmits a disconnection node notification frame from the third input / output port 21 and the fourth input / output port 22 (step S340B).

[0214] At this time, the slave transmission control unit 23 of the second slave 20B includes the MAC ID of the second slave 20B including the slave transmission control unit 23 in the disconnection node notification frame to be transmitted.

[0215] Here, when the detecting unit 25 of the second slave 20B detects recovery from the abnormality related to the connection of the third input / output port 21, the transmission path of the normal frame is the first redundant transmission path. Abnormal Due to the recovery, the transmission path for normal frames is changed from the first redundant transmission path to the main transmission path. Therefore, in the second slave 20B, the connection order from the controller 10 of the third slave 20C in the transmission path for normal frames is not changed. Therefore, the synchronization timing calculation unit 24 of the second slave 20B does not update the calculation method for the pulse timing T of the synchronization timing signal XSYNC.

[0216] In the processing of step S340B, when the slave transmission control unit 23 of the second slave 20B transmits a disconnection node notification frame from the fourth input / output port 22, the third input / output port 21 of the first slave 20A receives the disconnection node notification frame.

[0217] When the third input / output port 21 of the first slave 20A receives the disconnection node notification frame, the slave transmission control unit 23 of the first slave 20A transmits the disconnection node notification frame from the fourth input / output port 22 (step S340C).

[0218] When the second input / output port 12 receives the first disconnected node notification frame and the first input / output port 11 receives the second disconnected node notification frame, the controller transmission control unit 13 switches the operating mode from the second controller operating mode to the first controller operating mode (step S360).

[0219] The fourth operation performed by the communication system 1 changes the operation mode of the controller transmission control unit 13 from the second controller operation mode to the first controller operation mode. Also, the fourth operation performed by the communication system 1 changes the operation mode of the slave transmission control unit 23 of the third slave 20C from the second slave operation mode to the first slave operation mode. Also, the fourth operation performed by the communication system 1 changes the operation mode of the slave transmission control unit 23 of the second slave 20B from the second slave operation mode to the first slave operation mode. As a result, the transmission path of normal frames is changed from the first redundant communication path (see FIG. 6) to the main transmission path (see FIG. 4).

[0220] In this way, when the transmission path of a normal frame is the first redundant transmission path due to a cable breakage abnormality occurring in cable 30C, when the cable breakage abnormality in cable 30 is recovered, the communication system 1 changes the transmission path to the main transmission path and transmits the normal frame to each slave 20.

[0221] Hereinafter, the operation of the slave 20 and the operation of the controller 10 when the transmission path of the communication frame is the main transmission path in the initial state of the communication system 1 will be described.

[0222] 17 and 18 are flowcharts showing an example of the operation of the slave 20 when the transmission path of a communication frame is the main transmission path in the initial state of the communication system 1.

[0223] In the initial state of the communication system 1, as long as the slave 20 does not detect any abnormality in the connection (step S500: No) and as long as it does not receive a disconnected node notification frame (step S515: No), it repeatedly performs the process of receiving a normal frame on the upstream side of the main transmission path (step S545) and transmitting a normal frame from the downstream side of the main transmission path (step S550).

[0224] When the slave 20 detects a connection abnormality in the process of step S500 (step S500: Yes), it transmits a disconnection node notification frame from both the third input / output port 21 and the fourth input / output port 22 (step S505).

[0225] If the detection of the connection abnormality is a detection of an abnormality in the connection of the upstream input / output port of the main transmission path (step S510: Yes), the slave 20 updates the calculation method of the pulse timing T of the synchronization timing signal XSYNC (step S530).

[0226] When the slave 20 receives the disconnection node notification frame in the process of step S515 (step S515: Yes), the slave 20 checks whether the node count value included in the received disconnection node notification frame is 0 (step S520).

[0227] In the processing of step S520, if the node count value is 0 (step S520: Yes), and the disconnected node notification frame was received by an input / output port upstream of the main transmission path (step S525: Yes), the slave 20 updates the calculation method for the pulse timing T of the synchronization timing signal XSYNC (step S530).

[0228] In the processing of step S520, if the node count value is not 0 (step S520: No), and if the disconnection node notification frame is received by an input / output port upstream of the main transmission path (step S535: Yes), the slave 20 updates the calculation method for the pulse timing T of the synchronization timing signal XSYNC (step S540).

[0229] In the processing of step S510, if the detection of the connection abnormality is not the detection of an abnormality in the connection of the input / output port upstream of the main transmission path (step S510: No), if in the processing of step S525 the reception of the disconnected node notification frame is not by the input / output port upstream of the main transmission path (step S525: No), or if the processing of step S530 is completed, the slave 20 repeats the processing of receiving a normal frame at the input / output port on the side where the connection abnormality is not detected (step S600) and transmitting a normal frame from the input / output port on the side where the connection abnormality is not detected (step S625) as long as it does not detect recovery from the connection abnormality (step S605: No).

[0230] When the slave 20 detects recovery from the connection abnormality in the processing of step S605 (step S605: Yes), it transmits a disconnected node notification frame from both the third input / output port 21 and the fourth input / output port 22 (step S610).

[0231] If the detection of recovery from the connection abnormality is the detection of an abnormality in the connection of the upstream input / output port of the main transmission path (step S615: Yes), the slave 20 updates the calculation method for the pulse timing T of the synchronization timing signal XSYNC (step S620).

[0232] In the process of step S535, if the disconnection node notification frame is not received by the upstream input / output port of the main transmission path (step S535: No), or if the process of step S540 is completed, the slave 20 receives a normal frame (step S630), and so long as no disconnection node notification frame is received (step S635: No), the process of transmitting a normal frame from an input / output port different from the one used for reception (step S650) is repeated.

[0233] In the processing of step S635, if a disconnection node notification frame is received (step S635: Yes), and if the reception of the disconnection node notification frame was by an input / output port upstream of the main transmission path (step S640: Yes), the slave 20 updates the calculation method for the pulse timing T of the synchronization timing signal XSYNC (step S645).

[0234] In the processing of step S615, if the detection of recovery from the connection abnormality is not the detection of an abnormality related to the connection of the upstream input / output port of the main transmission path (step S615: No), if in the processing of step S640 the reception of the disconnected node notification frame is not received by the upstream input / output port of the main transmission path (step S640: No), if the processing of step S620 is completed, or if the processing of step S645 is completed, the slave 20 proceeds to the processing of step S500.

[0235] FIG. 19 is a flowchart showing an example of the operation of the controller 10 when the transmission path of a communication frame is the main transmission path in the initial state of the communication system 1.

[0236] In the initial state of the communication system 1, the controller 10 Main Transmission Path A normal frame is sent from the upstream input / output port (step S700), and the normal frame is received at the downstream input / output port on the main transmission path (step S760) as long as neither the first input / output port 11 nor the second input / output port 12 receives a disconnected node notification frame (step S705: No).

[0237] In the processing of step S700, when the controller 10 receives a disconnection node notification frame at both input / output ports (step S705: Yes), it checks whether the MACIDs included in the two received disconnection node notification frames are different from each other (step S710).

[0238] In the process of step S710, if the MACIDs included in the two received disconnection node notification frames are different from each other (step S710: Yes), the controller 10 determines that the abnormality that has occurred in the communication system 1 is a cable disconnection abnormality (step S715). Then, based on those MACIDs, the controller 10 determines that the location where the cable disconnection abnormality has occurred is between the slaves 20 with those MACIDs (step S720).

[0239] In the process of step S710, if the MACIDs included in the two received disconnection node notification frames are not different from each other (step S710: No), the controller 10 determines that the abnormality that occurred in the communication system 1 is a Phi terminal abnormality (step S725). Then, based on the node count values ​​included in the two disconnection node notification frames, the controller 10 determines that the location where the Phi abnormality occurred is between the two slaves 20 that transmitted disconnection node notification frames including a node count value indicating 1 (step S730).

[0240] When the processing of step S720 is completed and when the processing of step S730 is completed, the controller 10 repeatedly transmits a normal frame from both the first input / output port 11 and the second input / output port 12 (step S735), and receives a normal frame from both the first input / output port 11 and the second input / output port 12 (step S750) as long as a disconnected node notification frame is not received (step S740: No).

[0241] In the process of step S740, when the disconnection node notification frame is received (step S740: Yes), the controller 10 detects that the abnormality that occurred in the communication system 1 has been recovered from (step S755), and proceeds to the process of step S700.

[0242] [1-3. Discussion] According to the communication system 1 configured as described above, when the detection unit 25 in any of the slaves 20 detects an abnormality in the connection of the third input / output port 21 or an abnormality in the connection of the fourth input / output port 22, that is, when an abnormality in the network connection is detected, a disconnection node notification frame is transmitted from that slave 20 to the controller 10. As a result, the transmission path of normal frames in the communication system 1 is changed in a relatively short time after the abnormality in the network connection occurs.

[0243] In this way, the communication system 1 can reduce the time it takes from when an abnormality occurs in a network connection until the frame transmission path is changed, compared to conventional methods.

[0244] Furthermore, the communication system 1 configured as described above can determine the type of abnormality related to the network connection.

[0245] Furthermore, the communication system 1 configured as described above can determine the location where an abnormality related to the network connection has occurred.

[0246] Furthermore, according to the communication system 1 configured as described above, when the abnormality related to the network connection is recovered, the transmission path of the normal frame can be restored.

[0247] (Embodiment 2) A communication system according to a second embodiment, which is configured by partially modifying the communication system 1 according to the first embodiment, will be described below.

[0248] In the following, for the communication system of embodiment 2, components that are similar to those of communication system 1 of embodiment 1 have already been explained, so they will be assigned the same symbols and their detailed explanations will be omitted, and the explanation will focus on the differences from communication system 1.

[0249] The communication system according to the second embodiment is configured by changing the controller 10 in the communication system 1 according to the first embodiment to a controller 10A according to the second embodiment.

[0250] FIG. 20 is a block diagram showing an example of a functional configuration of the controller 10A according to the second embodiment.

[0251] As shown in FIG. 20, the controller 10A is configured by changing the controller transmission control section 13 of the controller 10 according to the first embodiment to a controller transmission control section 13A.

[0252] In addition to the functions of the controller transmission control unit 13, the controller transmission control unit 13A further has the following functions.

[0253] That is, the controller transmission control unit 13A receives a setting from a user of the communication system according to the second embodiment as to whether or not to stop transmitting normal frames when abnormalities occur in two or more locations in the communication system according to the second embodiment.

[0254] Then, when the controller transmission control unit 13A receives a setting to stop transmission of normal frames if abnormalities occur in two or more locations, in the communication system of embodiment 2, if abnormalities occur in two or more locations, the controller transmission control unit 13A stops transmission of normal frames.

[0255] The controller transmission control unit 13A may use, for example, an input interface (for example, a touchpad, a DIP switch, or the like) provided in the controller 10A to receive a setting as to whether or not to stop transmission of normal frames.

[0256] Furthermore, in the communication system according to the second embodiment, for example, when the controller transmission control unit 13A is operating in the first controller operation mode, if the first input / output port 11 and the second input / output port 12 each receive a disconnection node notification frame, and the sum of the node count values ​​contained in the disconnection node notification frames is less than the number of all slaves 20 stored in advance, the controller transmission control unit 13A may determine that an abnormality has occurred in two or more locations.

[0257] A user of the communication system according to the second embodiment having the above configuration may, for example, in the case where a malfunction occurs in the communication system according to the second embodiment because one or more slaves 20 are unable to receive normal frames, set the controller transmission control unit 13A to stop transmitting normal frames when an abnormality occurs in two or more places in the communication system according to the second embodiment.

[0258] A user of the communication system according to the second embodiment can set the controller transmission control unit 13A so that transmission of normal frames will not be stopped if abnormalities occur in two or more places in the communication system according to the second embodiment, thereby, for example, replacing one of the multiple slaves 20 included in the communication system according to the second embodiment without stopping the operation of the other slaves 20.

[0259] FIG. 21 is a schematic diagram showing a state in which a user of the communication system according to the second embodiment replaces one slave 20 (here, the third slave 20C) among the plurality of slaves 20 without stopping the operations of the other slaves 20 (here, the first slave 20A, the second slave 20B, and the fourth slave 20D).

[0260] 21, a user of the communication system according to the second embodiment removes the fourth input / output port 22 of the third slave 20C from the cable 30C and connects the fourth input / output port 22 of the fifth slave 20E instead. Also, the user removes the third input / output port 21 of the third slave 20C from the cable 30E and connects the third input / output port 21 of the fourth slave 20D instead. In this way, the third slave 20C can be replaced with the fifth slave 20E without stopping the operations of the first slave 20A, the second slave 20B, and the fourth slave 20D.

[0261] A user of the communication system according to the second embodiment can set the controller transmission control unit 13A so that transmission of normal frames will not be stopped if abnormalities occur in two or more places in the communication system according to the second embodiment, thereby, for example, removing one of the multiple slaves 20 included in the communication system according to the second embodiment without stopping the operation of the other slaves 20.

[0262] FIG. 22 is a schematic diagram showing a state in which a user of the communication system according to the second embodiment removes one slave 20 (here, the third slave 20C) from among the multiple slaves 20 without stopping the operations of the other slaves 20 (here, the first slave 20A, the second slave 20B, and the fourth slave 20D).

[0263] 22, a user of the communication system according to the second embodiment removes the fourth input / output port 22 of the fourth slave 20D and the third input / output port 21 of the third slave 20C from the cable 30E, removes the fourth input / output port 22 of the third slave 20C from the cable 30C, and connects the fourth input / output port 22 of the fourth slave 20D instead. In this way, the third slave 20C can be removed without stopping the operations of the first slave 20A, the second slave 20B, and the fourth slave 20D.

[0264] (Embodiment 3) FIG. 23 is a block diagram showing an example of the configuration of a communication system 1 according to the third embodiment.

[0265] As shown in FIG. 23, the communication system 1 includes a controller 10 having a first input / output port 11 and a second input / output port 12, and N slaves 20 each having a third input / output port 21 and a fourth input / output port 22. N is an integer equal to or greater than 2. In FIG. 23, the N slaves 20 include a first slave 20A, a K-1th slave 20 (K is an integer, 3≦K≦N−1), a Kth slave 20, and an Nth slave 20. As in the first embodiment, the first input / output port 11, the second input / output port 12, the third input / output port 21, and the fourth input / output port 22 are connected by a cable 30. That is, the communication system 1 according to the third embodiment represents a generalized communication system 1 having N slaves 20.

[0266] The communication system 1 according to the third embodiment can obtain the same effects as the communication system 1 according to the first embodiment.

[0267] (supplement) While the communication system according to one aspect of the present disclosure has been described above based on Embodiments 1 and 2, the present disclosure is not limited to these embodiments. As long as they do not deviate from the spirit of the present disclosure, various modifications conceivable by those skilled in the art to these embodiments and configurations constructed by combining components of different embodiments may also be included within the scope of one or more aspects of the present disclosure. [Industrial Applicability]

[0268] The present disclosure is widely applicable to communication systems and the like that include a controller and multiple slaves. [Explanation of symbols]

[0269] 1. Communication Systems 10, 10A controller 11 First input / output port 12 Second input / output port 13, 13A Controller transmission control section 14 Abnormal position determination section 15 Abnormality type determination section 20 Slave 20A First Slave 20B Second Slave 20C Third Slave 20D The Fourth Slave 20E The Fifth Slave 21 Third input / output port 22 Fourth I / O port 23 Slave transmission control section 24 Synchronization timing calculation section 25 Detector 30, 30A, 30B, 30C, 30D, 30E Cables 50 normal frames 101, 201 processors 102, 202 memory 110, 120, 210, 220 Connectors 111, 121, 211, 221 Transmit terminal TX 112, 122, 212, 222 Receiving terminal RX 130, 150, 230, 250 phi 131, 151, 231, 251 TX phi terminal 132, 152, 232, 252 RX phi terminal

Claims

1. a controller having a first input / output port, a second input / output port, and a controller transmission control unit; and first to Nth slaves (N is an integer of 2 or greater), each having a third input / output port, a fourth input / output port, a slave transmission control unit, and a detection unit; the first input / output port is connected to the fourth input / output port of the first slave; the third input / output port of the Nth slave is connected to the second input / output port; For any K (K is an integer between 2 and N), the third input / output port of the (K-1)th slave is connected to the fourth input / output port of the Kth slave; the controller transmission control unit generates and transmits a normal frame, receives a disconnection node notification frame, and executes a first controller operation mode and a second controller operation mode; the first controller operation mode includes repeatedly transmitting the normal frame from the first input / output port; the second controller operation mode includes repeatedly transmitting the normal frame from the first input / output port and the second input / output port; the slave transmission control unit transmits and receives the normal frame, generates the disconnection node notification frame, and transmits and receives the disconnection node notification frame, and executes a first slave operation mode and a second slave operation mode; the first slave operation mode is a mode in which, when one of the third input / output port and the fourth input / output port receives the normal frame, the other of the third input / output port and the fourth input / output port transmits the normal frame; In the second slave operation mode, when the one input / output port receives the normal frame, the one input / output port transmits the normal frame; the detection unit detects an abnormality related to a connection of the third input / output port and an abnormality related to a connection of the fourth input / output port; When the slave transmission control unit is operating in the first slave operation mode, if the detection unit detects an abnormality in the connection of the third input / output port or an abnormality in the connection of the fourth input / output port, switching from the first slave operation mode to the second slave operation mode, generating the disconnection node notification frame indicating that a change in connection state has been detected, and attempting to transmit the disconnection node notification frame from the third input / output port and the fourth input / output port; When the one input / output port receives the disconnection node notification frame, the other input / output port transmits the disconnection node notification frame; the controller transmission control unit further switches from the first controller operation mode to the second controller operation mode when the first input / output port or the second input / output port receives the disconnection node notification frame while operating in the first controller operation mode; Communication system.

2. the disconnection node notification frame includes a node count value indicating an integer value equal to or greater than 0, When the slave transmission control unit is operating in the first slave operation mode, (1) When the detection unit detects an abnormality in the connection of the one of the input / output ports, the detection unit attempts to transmit the disconnection-node notification frame including a node count value indicating 0 from the one of the input / output ports, and attempts to transmit the disconnection-node notification frame including a node count value indicating 1 from the other of the input / output ports; (2) when the one input / output port receives the disconnection node notification frame including a node count value indicating 0, switching from the first slave operation mode to the second slave operation mode; When the one input / output port receives the disconnection node notification frame, the one input / output port transmits the disconnection node notification frame from the other input / output port, the disconnection node notification frame including a node count value obtained by adding 1 to the node count value included in the disconnection node notification frame; When the first input / output port and the second input / output port receive the disconnection node notification frame, the controller compares a node count value included in the disconnection node notification frame received by the first input / output port with a previous node count value received by the second input / output port. The communication device further includes an abnormality position determination unit that determines the position where the abnormality has occurred based on the node count value included in the line break node notification frame. The communication system of claim 1 .

3. each of the first to Nth slaves further includes a synchronization timing calculation unit that calculates a synchronization timing signal indicating a synchronization timing at which the first to Nth slaves operate in synchronization, based on a timing at which the third input / output port or the fourth input / output port receives a normal frame; when the input / output port that receives the normal frame receives the disconnection node notification frame, and when the detection unit detects an abnormality in the connection of the input / output port that receives the normal frame, the synchronization timing calculation unit updates the calculation method for calculating the synchronization timing signal so that the synchronization timing does not change when the normal frame is received by an input / output port other than the input / output port that receives the normal frame. The communication system according to claim 2 .

4. the slave transmission control unit, when operating in the first slave operation mode, includes a MAC ID of the slave including the slave transmission control unit in the disconnection node notification frame that the detection unit attempts to transmit when it detects an abnormality related to the connection of the third input / output port or an abnormality related to the connection of the fourth input / output port; the controller further includes an abnormality type determination unit that, when the first input / output port and the second input / output port receive the disconnection node notification frame, determines a type of abnormality based on a MAC ID included in the disconnection node notification frame received by the first input / output port and a MAC ID included in the node notification frame received by the second input / output port; A communication system according to any one of claims 1 to 3.

5. the detection unit further detects recovery from an abnormality related to the connection of the third input / output port and recovery from an abnormality related to the connection of the fourth input / output port; The slave transmission control unit when the detection unit detects recovery from an abnormality related to the connection of the third input / output port or a abnormality related to the connection of the fourth input / output port while operating in the second slave operation mode, the operation mode is switched from the second slave operation mode to the first slave operation mode, and the disconnection node notification frame is transmitted from the third input / output port and the fourth input / output port; when the first input / output port or the second input / output port receives the disconnection node notification frame while operating in the second controller operation mode, the controller transmission control unit switches from the second controller operation mode to the first controller operation mode. A communication system according to any one of claims 1 to 4.

6. a first input / output port; a second input / output port; a slave transmission control unit; a detection unit, the slave transmission control unit transmits and receives normal frames, generates a disconnection node notification frame, and transmits and receives the disconnection node notification frame, and executes a first slave operation mode and a second slave operation mode; In the first slave operation mode, when one of the first input / output port and the second input / output port receives the normal frame, the other of the first input / output port and the second input / output port receives the normal frame. Send it from In the second slave operation mode, when the one input / output port receives the normal frame, the normal frame is transmitted from the one input / output port; the detection unit detects an abnormality related to a connection of the first input / output port and an abnormality related to a connection of the second input / output port; When the slave transmission control unit is operating in the first slave operation mode, if the detection unit detects an abnormality in the connection of the first input / output port or an abnormality in the connection of the second input / output port, switching from the first slave operation mode to the second slave operation mode, generating the disconnection node notification frame indicating that a change in connection state has been detected, and attempting to transmit the disconnection node notification frame from the first input / output port and the second input / output port; When the one input / output port receives the disconnection node notification frame, the one input / output port transmits the disconnection node notification frame from the other input / output port. Slave.

7. the disconnection node notification frame includes a node count value indicating an integer value equal to or greater than 0, When the slave transmission control unit is operating in the first slave operation mode, (1) When the detection unit detects an abnormality related to the connection of the first input / output port, the detection unit attempts to transmit the disconnection-node notification frame including a node count value indicating 0 from the one input / output port, and attempts to transmit the disconnection-node notification frame including a node count value indicating 1 from the other input / output port; (2) when the one input / output port receives the disconnection node notification frame including a node count value indicating 0, switching the operation mode from the first slave operation mode to the second slave operation mode; When the one input / output port receives the disconnection node notification frame, the other input / output port transmits a disconnection node notification frame including a node count value obtained by adding 1 to the node count value included in the disconnection node notification frame. The slave according to claim 6.

8. a synchronization timing calculation unit that calculates a synchronization timing signal indicating synchronization timing based on a timing at which the first input / output port or the second input / output port receives a normal frame; when the input / output port that receives the normal frame receives the disconnection node notification frame, and when the detection unit detects an abnormality in the connection of the input / output port that receives the normal frame, the synchronization timing calculation unit updates the calculation method for calculating the synchronization timing signal so that the synchronization timing does not change when the normal frame is received by an input / output port other than the input / output port. The slave according to claim 7.

9. When the slave transmission control unit is operating in the first slave operation mode, When the detection unit detects an abnormality in the connection of the first input / output port or an abnormality in the connection of the second input / output port, The MAC ID of the slave including the slave transmission control unit is included in the disconnection node notification frame to be transmitted. The slave according to any one of claims 6 to 8.

10. the detection unit further detects recovery from an abnormality related to the connection of the first input / output port and recovery from an abnormality related to the connection of the second input / output port; The slave transmission control unit When operating in the second slave operation mode, When the detection unit detects recovery from an abnormality related to the connection of the first input / output port or recovery from an abnormality related to the connection of the second input / output port, switching from the second slave operation mode to the first slave operation mode and transmitting the disconnection node notification frame from the first input / output port and the second input / output port; A slave according to any one of claims 6 to 9.

11. a first input / output port; a second input / output port; a controller transmission control unit; the controller transmission control unit generates and transmits a normal frame, receives a disconnection node notification frame, and executes a first controller operation mode and a second controller operation mode; In the first controller operation mode, the normal frame is repeatedly transmitted from the first input / output port; in the second controller operation mode, repeatedly transmitting the normal frame from the first input / output port and the second input / output port; when the first input / output port or the second input / output port receives a disconnection node notification frame indicating that a change in connection state has been detected while operating in the first controller operation mode, the mode is switched from the first controller operation mode to the second controller operation mode; In the controller, The disconnection node notification frame includes a MAC ID, and an abnormality type determination unit that, when the first input / output port and the second input / output port receive the disconnection node notification frame, determines the type of abnormality based on a MAC ID included in the disconnection node notification frame received by the first input / output port and a MAC ID included in the disconnection node notification frame received by the second input / output port. controller.

12. When the first input / output port or the second input / output port receives a disconnection node notification frame while operating in the second controller operation mode, the operation mode is switched from the second controller operation mode to the first controller operation mode. The controller of claim 11.

13. A system comprising: a controller having a first input / output port, a second input / output port, and a controller transmission control unit; and first to Nth slaves (N is an integer of 2 or greater) each having a third input / output port, a fourth input / output port, a slave transmission control unit, and a detection unit; A communication method performed by a communication system in which the first input / output port and the fourth input / output port of the first slave are connected, the third input / output port and the second input / output port of the Nth slave are connected, and for any K (K is an integer between 2 and N), the third input / output port of a K-1th slave and the fourth input / output port of a Kth slave are connected, In the controller transmission control unit, a normal frame is generated and transmitted, a disconnection node notification frame is received, and a first controller operation mode and a second controller operation mode are executed; In the first controller operation mode, the normal frame is repeatedly transmitted from the first input / output port; in the second controller operation mode, repeatedly transmitting the normal frame from the first input / output port and the second input / output port; In each of the first slave to the Nth slave, The slave transmission control unit in a first slave operation mode, when one of the third input / output port and the fourth input / output port receives the normal frame, the other of the third input / output port and the fourth input / output port transmits the normal frame; In a second slave operation mode, when the one input / output port receives the normal frame, the one input / output port transmits the normal frame; the detection unit detects an abnormality related to a connection of the third input / output port and an abnormality related to a connection of the fourth input / output port; When the slave transmission control unit is further operating in the first slave operation mode, if the detection unit detects an abnormality in the connection of the third input / output port or an abnormality in the connection of the fourth input / output port, switching from the first slave operation mode to the second slave operation mode, generating the disconnection node notification frame indicating that a change in connection state has been detected, and attempting to transmit the disconnection node notification frame from the third input / output port and the fourth input / output port; When the one input / output port receives the disconnection node notification frame, the other input / output port transmits the disconnection node notification frame; When the first input / output port or the second input / output port receives the disconnection node notification frame while the controller transmission control unit is operating in the first controller operation mode, the controller transmission control unit switches from the first controller operation mode to the second controller operation mode. Communication method.

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