Redundant system, and controller

Abstract

To make, redundant, a path of a network in which devices are daisy-chained with a serial communication line.SOLUTION: A redundant system 100 includes: a first controller 1; and one or more devices 50 daisy-chained to the first controller 1 in a ring shape with a serial communication line 30. The first controller 1 includes: a first port 11 to which one end of the serial communication line 30 is connected; a second port 12 to which the other end of the serial communication line 30 is connected; and a communication unit 13 that can access the devices 50 around a first direction from the first port 11 to the second port 12 or around a second direction from the second port 12 to the first port 11 and perform serial communication.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This invention relates to a redundant system with redundant network paths and a controller that constitutes the redundant system.

Background Art

[0002] In recent years, in building automation systems, BACnet (Building Automation and Control Network) communication, which is an open protocol, has been widely popularized. As communication protocols used in BACnet communication, the "BACnet IP" protocol for communicating BACnet services over Ethernet and the "BACnet MS / TP (Master Slave Token Passing)" protocol that uses RS485 for the physical layer of data transmission are known. Among these, the "BACnet MS / TP" protocol is a protocol that combines two communication methods, a master-slave communication method and a token passing communication method, for communication. A conventional system configuration example to which this BACnet MS / TP protocol is applied is shown in FIG. 17.

[0003] In the system shown in FIG. 17, according to the RS485 communication standard of the physical layer, a general controller 1000 as a master node and a secondary device (field device) 50 as a slave node are connected in a daisy chain manner (so-called series connection) via a serial communication line (MSTP line) 30. The general controller 1000 has two ports (a first port 1011 and a second port 1012) to which the serial communication line 30 can be connected, and the serial communication line 30 is connected to each port. Then, the general controller 1000 monitors the states of the secondary devices 50 connected to the respective serial communication lines 30 via the respective serial communication lines 30.

[0004] Specifically, in this system, a token (communication right) circulates on the network in ascending order of serial addresses, and the node that acquires this token can communicate with other nodes. The general-purpose controller 1000 monitors the status of the secondary device 50 by acquiring (scanning) the status information of the secondary device 50 connected to each serial communication line 30 at the timing when the token is acquired. In FIG. 17, reference numeral 80 is an integrated controller 80 which is a higher-level controller of the general-purpose controller 1000, and reference numeral 70 is a communication line connecting the general-purpose controller 1000 and the integrated controller 80.

[0005] Here, when a disconnection occurs in the middle of the serial communication line 30, the general-purpose controller 1000 may not be able to access the secondary device 50 connected beyond the point where the disconnection of the serial communication line 30 occurred, and may not be able to acquire the status information of the secondary device 50.

[0006] On the other hand, various techniques have been proposed to solve the problems caused by such line failures. For example, Patent Document 1 discloses a ring network system that quickly switches the path when a line failure occurs.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, the technology described in Patent Document 1 is a technology for redundant routing in a system using a standard technology, the Resilient Packet Ring (RTP) ring network. And the network configuration to which this technology is applied is fundamentally different from the network configuration in which the secondary device 50 is connected to the serial communication line 30 in a daisy chain manner. Therefore, it was difficult to apply the technology described in Patent Document 1 to a network configured by the serial communication line 30 as shown in FIG. 17.

[0009] The present invention has been made to solve the above problems, and an object thereof is to provide a redundant system capable of redundant routing of a network configured by daisy-chain connecting devices via a serial communication line.

Means for Solving the Problems

[0010] The redundant system according to the present invention includes a first controller and one or more devices daisy-chain connected to the first controller in a ring shape via a serial communication line. The first controller includes a first port to which one end of the serial communication line is connected, a second port to which the other end of the serial communication line is connected, and a communication unit capable of accessing the devices around a first direction from the first port to the second port or around a second direction from the second port to the first port for serial communication. The communication unit includes a status information acquisition unit that acquires the status information of the device by serial communication. The status information acquisition unit sequentially accesses the devices around either the first direction or the second direction to acquire the status information of each device. As a result, if the status information cannot be acquired from any of the devices, the access direction is switched to the other direction around the first direction or the second direction, and the devices are sequentially accessed to acquire the status information. The first controller includes a disconnection determination unit that determines whether a disconnection has occurred in the serial communication line based on the acquisition result of the status information by the status information acquisition unit. The disconnection determination unit determines that a disconnection has occurred in the serial communication line when the acquisition result of the status information when the status information acquisition unit accesses around either the first direction or the second direction is inverted with respect to the acquisition result of the status information when accessing around the other direction, and the inverted acquisition results are continuously obtained a predetermined number of times.

Effects of the Invention

[0011] According to the present invention, since it is configured as described above, it is possible to redundant the routing of a network configured by daisy-chain connecting devices via a serial communication line.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Embodiment 1. FIG. 1 is a diagram showing a configuration example of a redundant system 100 according to Embodiment 1.

[0014] The redundant system 100 includes a general-purpose controller (first controller) 1 and one or more secondary devices 50 connected in a ring shape to the general-purpose controller 1 by a serial communication line 30. The secondary devices 50 are connected to the general-purpose controller 1 in a daisy-chain manner via the serial communication line 30.

[0015] The general-purpose controller 1 monitors the states of the secondary devices 50 via the serial communication line 30. In the redundant system 100, as described above, a token (communication right) circulates on the network in ascending order of serial addresses, and the node that has acquired this token communicates with other nodes. The general-purpose controller 1 monitors the states of the respective secondary devices 50 by acquiring (scanning) the state information (life and death information) of each secondary device 50 connected to the serial communication line 30 at the timing when it acquires the token. Further, the general-purpose controller 1 accesses the secondary device 50 at the timing when it acquires the token, and acquires various types of information other than the state information held by the device 50 (hereinafter referred to as held information). The serial addresses are assigned in advance by an engineer to the general-purpose controller 1 and each secondary device 50.

[0016] The secondary device 50 is a field device from which the general-purpose controller 1 acquires status information or holding information. The secondary device 50 is composed of, for example, a controller that controls a Variable Air Volume (VAV) device in air-conditioning control, a controller that controls a Fan Coil Unit (FCU) in air-conditioning control, and the like.

[0017] Note that the integrated controller 80 is a higher-level controller that integrally manages lower-level controllers including the general-purpose controller 1, and is connected to the general-purpose controller 1 via a communication line 70 different from the serial communication line 30. The integrated controller 80 holds schedule information of the secondary device 50 (such as an air conditioner) that the general-purpose controller 1 monitors. The integrated controller 80 instructs the general-purpose controller 1 to turn the secondary device 50 ON / OFF (start / stop) etc. according to this schedule information. Note that the communication line 70 is a communication line capable of Ethernet communication based on the "BACnet IP" protocol, and the integrated controller 80 and the general-purpose controller 1 can perform Ethernet communication via the communication line 70.

[0018] Next, a configuration example of the general-purpose controller 1 will be described. As shown in FIG. 2, the general-purpose controller 1 includes a first port 11, a second port 12, a communication unit 13 (status information acquisition unit 131 and holding information acquisition unit 132), and a storage unit 14.

[0019] The first port 11 is a physical port (terminal) to which one end of the serial communication line 30 is connected. The second port 12 is a physical port (terminal) to which the other end of the serial communication line 30 is connected.

[0020] The communication unit 13 accesses the secondary device 50 around a first direction from the first port 11 to the second port 12 or around a second direction from the second port 12 to the first port 11, and performs serial communication with the device 50.

[0021] In addition, the engineer may preset which port of the first port 11 and the second port 12 to preferentially use. For example, when the engineer sets the first port 11 as the preferentially used port, the communication unit 13 preferentially accesses the secondary device 50 around the first direction from the first port 11 to the second port 12.

[0022] The communication unit 13 includes a status information acquisition unit 131 and a held information acquisition unit 132. Among them, the status information acquisition unit 131 sequentially accesses the secondary device 50 around one of the first direction or the second direction, and acquires the status information of each device 50. As a result, if the status information cannot be acquired from any of the secondary devices 50, the status information acquisition unit 131 switches the access direction to the other of the first direction or the second direction, and sequentially accesses the secondary device 50 to acquire the status information of the remaining devices 50 including the device 50 from which the status information could not be acquired.

[0023] The held information acquisition unit 132 accesses the secondary device 50 in the first direction or the second direction based on the acquisition result of the status information by the status information acquisition unit 131, and acquires the information (held information) held by the device 50 other than the status information.

[0024] The functions of the communication unit 13 (the status information acquisition unit 131 and the held information acquisition unit 132) are realized, for example, by a CPU (Central Processing Unit) (not shown) provided in the general-purpose controller 1 executing a predetermined program developed in the memory.

[0025] The storage unit 14 stores various information used by the general-purpose controller 1. For example, the storage unit 14 stores the acquisition result of the state information by the state information acquisition unit 131, the acquisition result of the retention information by the retention information acquisition unit 132, and information such as the serial address assigned to each device. The storage unit 14 is composed of, for example, an HDD (Hard Disc Drive), an SSD (Solid State Drive), or a memory. In FIG. 2, the case where the storage unit 14 is provided inside the general-purpose controller 1 is shown, but the storage unit 14 may be provided outside the general-purpose controller 1.

[0026] Next, an outline of the operation example of the general-purpose controller 1 will be described. As described above, the general-purpose controller 1 includes the first port 11 and the second port 12 as physical ports to which the serial communication line 30 is connected. In the general-purpose controller 1, these first port 11 and second port 12 correspond to channels (1CH and 2CH) for performing serial communication with the secondary device 50.

[0027] Also, in the general-purpose controller 1, serial addresses are assigned to each channel in advance by an engineer. For example, the serial address "0" is assigned to the first port 11 (1CH) and the serial address "127" is assigned to the second port 12 (2CH) by the engineer. Similarly, serial addresses "1" to "126" are assigned to the secondary device 50 by the engineer according to the daisy-chain order.

[0028] And in the redundant system 100, according to the specifications of the BACnet MSTP protocol, the token circulates on the serial communication line 30 in the order of serial addresses. That is, the token circulates from the device with the serial address 0 (here, the first port 11) in the order of devices with serial addresses 1, 2,... 126, and finally reaches the device with the serial address 127 (here, the second port 12).

[0029] When the general-purpose controller 1 acquires a token, it acquires (scans) the status information of the secondary device 50. For example, when the first port 11 (1CH) is set as the port preferentially used by an engineer, the status information acquisition unit 131 of the general-purpose controller 1 first sequentially accesses the secondary device 50 in the first direction from the first port 11 (1CH) to the second port 12 (2CH) based on the serial address information stored in the storage unit 14, and acquires the status information of the device 50.

[0030] The acquisition of this status information is performed in the range from the device with the serial address "1" to the device with the serial address "126". The status information acquisition unit 131 may store the acquisition result of the status information in the storage unit 14. For example, when the status information acquisition unit 131 can acquire the status information from the device 50 (there is a response to the scan), it stores in the storage unit 14 an acquisition result indicating that the status information of the device 50 has been acquired. On the other hand, when the status information acquisition unit 131 cannot acquire the status information from the device 50 (there is no response to the scan), it stores in the storage unit 14 an acquisition result indicating that the status information of the device 50 cannot be acquired.

[0031] For example, as an example, consider the case where there is no disconnection in the serial communication line 30 as shown in FIG. 3. The status information acquisition unit 131 accesses the secondary device 50 in the first direction (reference P in FIG. 3) from the first port 11 (1CH) to the second port 12 (2CH), and acquires the status information of the device 50. At this time, in FIG. 3, since there is no disconnection in the serial communication line 30, it is assumed that the status information acquisition unit 131 can acquire the status information of all the secondary devices 50.

[0032] An example of the acquisition result in this case is shown in FIG. 4. In FIG. 4, the acquisition result of the state information is stored in the storage unit 14 in a table format. In the table of FIG. 4, "OK(1)" is described in the column of "This Check Result". This indicates that the state information acquisition unit 131 has successfully acquired the state information. Note that "1" is described in the column of "Priority Scan Use CH", which indicates that the channel used when acquiring the held information of each device is 1CH (the first port 11).

[0033] Next, as shown in FIG. 5, consider the case where a disconnection occurs in the serial communication line 30. In FIG. 5, a disconnection occurs in the serial communication line 30 at the location marked with symbol A. In this case, the state information acquisition unit 131 accesses the secondary device 50 around the first direction (symbol P in FIG. 5) from the first port 11 (1CH) to the second port 12 (2CH) and acquires the state information of the device 50. Although the state information of the device 50 before the disconnection location in the first direction can be acquired, it is assumed that the state information of the device 50 after the disconnection location cannot be acquired.

[0034] An example of the acquisition result in this case is shown in FIG. 6. In the table of FIG. 6, for the device 50 before the disconnection location, "OK(1)" is described in the column of "This Check Result", but for the device 50 after the disconnection location, "NG(0)" is described in the column of "Check Result". This "NG(0)" indicates that the state information acquisition unit 131 has failed to acquire the state information. Note that the time during which the state information acquisition unit 131 fails to acquire the state information is described in the column of "NG Duration" in the table of FIG. 6.

[0035] As described above, as a result of acquiring status information around the first direction, if there is even one device that failed to acquire status information, the status information acquisition unit 131 switches the access direction to the secondary device 50. That is, the status information acquisition unit 131 accesses the secondary device 50 in the second direction (reference symbol Q in FIG. 5) from the second port 12 (2CH) to the first port 11 (1CH), which is opposite to the first direction, and acquires the status information of the device 50.

[0036] An example of the acquisition result in this case is shown in FIG. 7. It can be seen that the description in the "Check Result" column in the table of FIG. 7 is reversed from the table of FIG. 6. Also, if a device 50 that failed to acquire status information in the first direction succeeds in acquiring status information in the second direction, "2" is described in the "Priority Scan Use CH" column for that device 50. This indicates that channel 2CH (second port 12) is used to acquire the information held by the device 50.

[0037] In addition, if the disconnection that occurred at the location of reference symbol A in FIG. 5 is restored, and for a device 50 that failed to acquire status information in the first direction before restoration, if it succeeds in acquiring status information in the first direction at the timing after restoration, the status information acquisition unit 131 rewrites the acquisition result as shown in FIG. 8. That is, for a device 50 that has succeeded in acquiring status information in the first direction, the status information acquisition unit 131 clears the "NG Duration" and returns the "Priority Scan Use CH" from "2" to "1".

[0038] Next, with reference to FIG. 9, the details of the operation example of the general-purpose controller 1 according to Embodiment 1 will be described. It is assumed that the general-purpose controller 1 executes the following processing each time it acquires a token. Also, in the following, it is assumed that the first port 11 is set in advance by an engineer to be the port preferentially used. Further, in the following, an example in which the status information acquisition unit 131 stores the acquisition result of the status information in the storage unit 14 will be described, but the status information acquisition unit 131 does not necessarily have to store the acquisition result of the status information in the storage unit 14.

[0039] First, the status information acquisition unit 131 accesses the secondary device 50 in the first direction from the first port 11 (1CH) to the second port 12 (2CH), and acquires the status information of the device 50 (step ST901).

[0040] Next, the status information acquisition unit 131 stores the acquisition result of the status information when accessing in the first direction in the storage unit 14 (step ST902).

[0041] Next, the status information acquisition unit 131 refers to the acquisition result of the status information stored in step ST902, and checks whether there is a device for which the acquisition of the status information has failed (step ST903). As a result, if there is no device for which the acquisition of the status information has failed (step ST903; NO), the general-purpose controller 1 ends the process.

[0042] On the other hand, if there is a device for which the acquisition of the status information has failed (step ST903; YES), the status information acquisition unit 131 accesses the secondary device 50 in the second direction from the second port 12 (2CH) to the first port 11 (1CH), and acquires the status information of the device 50 (step ST904).

[0043] Next, the status information acquisition unit 131 stores the acquisition result of the status information when accessing in the second direction in the storage unit 14 (step ST905), and ends the process.

[0044] As described above, according to the first embodiment, the redundant system 100 includes a general-purpose controller 1 and one or more devices 50 daisy-chain connected to the general-purpose controller 1 in a ring shape by a serial communication line 30. The general-purpose controller 1 includes a first port 11 to which one end of the serial communication line 30 is connected, a second port 12 to which the other end of the serial communication line 30 is connected, and a communication unit 13 capable of accessing the device 50 in the first direction from the first port 11 to the second port 12 or in the second direction from the second port 12 to the first port 11 for serial communication. Thereby, the redundant system 100 can redundantize the path of the network configured by daisy-chain connecting the devices 50 by the serial communication line 30. Further, the redundant system 100 is also effective in terms of cost. For example, in the above Patent Document 1, two ring node devices are used to redundantize the path, but in the first embodiment, a redundant system can be realized with one general-purpose controller 1, and a redundant system can be constructed at a lower cost compared to the above Patent Document 1.

[0045] Further, the communication unit 13 includes a status information acquisition unit 131 that acquires the status information of the device 50 by serial communication. When the status information acquisition unit 131 sequentially accesses the device 50 in either the first direction or the second direction and fails to acquire the status information from any of the devices 50, the access direction is switched to the other direction of the first direction or the second direction, and the device 50 is sequentially accessed to acquire the status information. Thereby, even if there is a device 50 that fails to acquire the status information in either one of the directions, the general-purpose controller 1 can access the device 50 in the other direction, and can continuously acquire the status information and monitor the device 50 based on the acquired status information.

[0046] In addition, the general-purpose controller 1 includes a first port 11 to which one end of a serial communication line 30 is connected, where one or more devices 50 are daisy-chain connected in a ring shape, a second port 12 to which the other end of the serial communication line 30 is connected, and a communication unit 13 capable of accessing the device 50 in a first direction around from the first port 11 to the second port 12 or in a second direction around from the second port 12 to the first port 11 for serial communication. Thereby, the general-purpose controller 1 can continuously perform serial communication with the device 50.

[0047] Embodiment 2. In Embodiment 1, an example in which the general-purpose controller 1 accesses the secondary device 50 in the first direction around or the second direction around and communicates with the device 50 was described. In addition to this, in Embodiment 2, an example in which the general-purpose controller 1 determines whether or not a disconnection has occurred in the serial communication line 30 based on the acquisition result of the state information of the secondary device 50 will be described.

[0048] FIG. 10 is a diagram showing a configuration example of the general-purpose controller 1b according to Embodiment 2. The general-purpose controller 1b according to Embodiment 2 has a disconnection determination unit 15 added to the general-purpose controller 1 according to Embodiment 1. Since the other configurations of the general-purpose controller 1b are the same as those of the general-purpose controller 1 according to Embodiment 1, the same reference numerals are given and the description thereof is omitted.

[0049] The disconnection determination unit 15 determines whether or not a disconnection has occurred in the serial communication line 30 based on the acquisition result of the state information by the state information acquisition unit 131.

[0050] For example, when the acquisition result of the state information by the state information acquisition unit 131 is as shown in FIG. 4, that is, when there is no device that has failed to acquire the state information when the state information acquisition unit 131 accesses the secondary device 50 in the first direction around, the disconnection determination unit 15 determines that no disconnection has occurred in the serial communication line 30.

[0051] On the other hand, when the acquisition results of the state information by the state information acquisition unit 131 are in an inverted relationship as shown in FIGS. 6 and 7, and these acquisition results are continuously obtained a predetermined number of times, the disconnection determination unit 15 determines that a disconnection has occurred in the serial communication line 30. That is, the disconnection determination unit 15 determines that there is an inverted relationship between the acquisition result of the state information when accessing around the first direction and the acquisition result of the state information when accessing around the second direction, and when the inverted acquisition results are continuously obtained a predetermined number of times, it is determined that a disconnection has occurred in the serial communication line 30. Thereby, the disconnection determination unit 15 prevents misjudging that a disconnection has occurred in the serial communication line 30 due to a temporary restart of the device 50 or the influence of noise.

[0052] Note that the disconnection determination unit 15 may determine whether a disconnection has occurred in the serial communication line 30 by the above method at the timing after the state information acquisition unit 131 has acquired the state information as shown in FIG. 4, or at the timing after the state information acquisition unit 131 has acquired the state information as shown in FIGS. 6 and 7.

[0053] Note that the disconnection determination unit 15 may also determine whether disconnections have occurred at a plurality of locations on the serial communication line 30 as follows.

[0054] For example, as shown in FIG. 11, when disconnections have occurred at a plurality of locations (here, two locations denoted by reference signs A and B) on the serial communication line 30, it is assumed that the state information acquisition unit 131 cannot acquire the state information regardless of whether it accesses around the first direction or the second direction for the device 50 located between the disconnection locations.

[0055] An example of the acquisition result of the information in this case is shown in FIG. 12. FIG. 12A shows the acquisition result of the state information around the first direction, and FIG. 12B shows the acquisition result of the state information around the second direction. As shown in FIGS. 12A and 12B, here, for two devices 50 (Device E) with serial addresses "31" and "32", accessing in any direction fails to obtain status information. Also, the "NG duration", which indicates the duration during which the failure to obtain the status information of each device 50 continues, is 60 seconds. Thus, when the "NG duration" is equal to or longer than a predetermined time (for example, 60 seconds or longer) and there are a predetermined number or more (for example, two or more) of devices 50 with the same "NG duration", the disconnection determination unit 15 determines that disconnections have occurred at multiple locations on the serial communication line 30. The predetermined time and the predetermined number in this case can be set to appropriate values by an engineer.

[0056] As described above, according to the second embodiment, the general-purpose controller 1 includes a disconnection determination unit 15 that determines whether a disconnection has occurred on the serial communication line 30 based on the result of obtaining status information by the status information acquisition unit 131. Thereby, the general-purpose controller 1 can determine whether a disconnection has occurred on the serial communication line 30.

[0057] Further, the disconnection determination unit 15 determines that a disconnection has occurred on the serial communication line 30 when the result of obtaining status information when the status information acquisition unit 131 accesses in one of the first direction or the second direction is reversed from the result of obtaining status information when accessing in the other direction, and the reversed acquisition results are continuously obtained a predetermined number of times. Thereby, the disconnection determination unit 15 can prevent misjudging that a disconnection has occurred on the serial communication line 30 due to a temporary restart of the device 50 or the influence of noise.

[0058] Further, when the duration of the state in which the state information acquisition unit 131 fails to acquire the state information regardless of whether it accesses around the first direction or the second direction is equal to or longer than a predetermined time, and there are a predetermined number or more of the same devices with such a duration, the disconnection determination unit 15 determines that a plurality of disconnections have occurred in the serial communication line 30. Thereby, even when a plurality of disconnections occur in the serial communication line 30, the disconnection determination unit 15 can appropriately determine the presence or absence of the occurrence of the plurality of disconnections.

[0059] Embodiment 3. In Embodiment 3, a communication example between an operating device and a general-purpose controller will be described in a case where a part of the secondary device 50 is configured by the operating device.

[0060] The operating device is a device configured by at least one of the secondary devices 50, and is a device that receives an operation from an engineer (user) and can access the general-purpose controller 1 and the integrated controller 80 according to the operation.

[0061] For example, the operating device acquires information held by the general-purpose controller 1 by accessing (sending an access request to) the general-purpose controller 1 and displays it on the display unit, or updates the information held by the general-purpose controller 1, thereby indirectly operating the secondary device 50. Further, the operating device accesses the integrated controller 80 via the general-purpose controller 1 to change the setting of schedule information of various devices such as an air conditioner stored in the integrated controller 80. For example, when the operating device receives an instruction from the user to extend the operation time of the air conditioner, the operating device sends an access request to the integrated controller 80 to change the schedule information of the air conditioner stored in the integrated controller 80.

[0062] On the other hand, the operator cannot determine on its own whether there is a disconnection in the serial communication line 30. Therefore, the general-purpose controller 1c according to Embodiment 3 generates information (gateway device information) indicating which of the first port 11 and the second port 12 of its own device is the gateway device based on the determination result by the disconnection determination unit 15, and transmits it to the secondary device 50 including the operator. By receiving the gateway device information, the operator recognizes which of the first port 11 and the second port 12 is the available gateway device. Then, the operator transmits an access request to the gateway device indicated by the gateway device information to the general-purpose controller 1c and the integrated controller 80.

[0063] FIG. 13 is a diagram showing a configuration example of the general-purpose controller 1c according to Embodiment 3. In the general-purpose controller 1c according to Embodiment 3, a transmission unit 16, a reception unit 17, a response unit 18, and a transfer unit 19 are added to the general-purpose controller 1b according to Embodiment 2. Since the other configurations of the general-purpose controller 1c are the same as those of the general-purpose controller 1b according to Embodiment 2, the same reference numerals are given and the description thereof is omitted.

[0064] The transmission unit 16 generates the above-described gateway device information based on the determination result by the disconnection determination unit 15, and transmits the information to the secondary device 50 including the operator.

[0065] Specifically, when the disconnection determination unit 15 determines that there is no disconnection in the serial communication line 30, the transmission unit 16 generates gateway device information indicating that either the first port 11 or the second port 12 is the gateway device by the "I-AM-ROUTER" service defined in BACnet, and transmits the generated information to the secondary device 50 all at once by broadcasting. If a port to be preferentially used is set, the transmission unit 16 may generate information indicating that the preferentially used port is the gateway device.

[0066] Further, when the disconnection determination unit 15 determines that a disconnection has occurred in the serial communication line 30, the transmission unit 16 generates information indicating that the first port 11 is a gateway device (first gateway device information) and information indicating that the second port 12 is a gateway device (second gateway device information) by the "I-AM-ROUTER" service defined in BACnet. Then, when the state information acquisition unit 131 can acquire state information when accessing around the first direction, the transmission unit 16 broadcasts and distributes the first gateway device information all at once from the first port 11 to the secondary device 50 that has acquired the state information. When the state information acquisition unit 131 can acquire state information when accessing around the second direction, the transmission unit 16 broadcasts and distributes the second gateway device information all at once from the second port 12 to the secondary device 50 that has acquired the state information.

[0067] Note that the generation and transmission of the gateway device information by the transmission unit 16 may be performed at a timing after the disconnection determination unit 15 determines whether or not a disconnection has occurred in the serial communication line 30.

[0068] The reception unit 17 receives an access request for the own device or the integrated controller 80 transmitted from an access unit 62 (to be described later) of the operator.

[0069] When the access request received by the reception unit 17 is a request for the own device, the response unit 18 responds to the access request. For example, when the access request received by the reception unit 17 is a request for acquiring temperature, humidity, CO2 concentration, etc. of the own device, as a response, the response unit 18 transmits information such as the requested temperature, humidity, and CO2 concentration to the operator 60.

[0070] When the access request received by the reception unit 17 is for the integrated controller 80, the transfer unit 19 transfers the access request to the integrated controller 80 via the communication line 70.

[0071] Next, a configuration example of the operator is shown in FIG. 14. In FIG. 14, reference numeral 60 denotes the operator. As shown in FIG. 14, the operator 60 includes a receiving unit 61, an access unit 62, a storage unit 63, and a display unit 64.

[0072] The receiving unit 61 receives the gateway device information transmitted from the transmitting unit 16 of the general-purpose controller 1c. Further, the receiving unit 61 receives the information transmitted from the response unit 18 of the general-purpose controller 1c, that is, the information transmitted as a response to the access request from the access unit 62 (for example, information such as temperature, humidity, and CO2 concentration). The receiving unit 61 may store the received gateway device information and the information received as a response to the access request from the access unit 62 in the storage unit 63.

[0073] The access unit 62 generates an access request in response to an instruction received from the user via, for example, the display unit 64, and transmits the generated access request to the general-purpose controller 1c. At this time, the access unit 62 transmits an access request to the gateway device of the general-purpose controller 1c indicated by the gateway device information received by the receiving unit 61. The transmitted access request is received by the receiving unit 17 of the general-purpose controller 1c via the gateway device of the general-purpose controller 1c.

[0074] The storage unit 63 stores various information used by the operator 60. For example, the storage unit 63 stores the gateway device of the general-purpose controller 1c indicated by the gateway device information received by the receiving unit 61 and the information received by the receiving unit 61 from the response unit 18 of the general-purpose controller 1c. The storage unit 63 is composed of, for example, an HDD (Hard Disc Drive), an SSD (Solid State Drive), or a memory. In FIG. 14, the case where the storage unit 63 is provided inside the operator 60 is shown, but the storage unit 63 may be provided outside the operator 60.

[0075] The display unit 64 displays the information (such as temperature, humidity, and CO2 concentration, etc.) received by the reception unit 61 from the response unit 18 of the general-purpose controller 1c. Further, the display unit 64 displays various screens such as a screen for operating the ON / OFF of the air conditioner or a screen for changing the schedule information of the air conditioner.

[0076] As described above, when transmitting an access request, the access unit 62 transmits an access request to the gateway device indicated by the gateway device information received by the reception unit 61. In other words, even when the gateway device indicated by the gateway device information changes, the access unit 62 can appropriately switch the access path to the general-purpose controller 1c according to the change. Thereby, even when a disconnection occurs in the serial communication line 30, the operator 60 can appropriately switch the access path and continue operating.

[0077] As described above, according to the third embodiment, the general-purpose controller 1c includes a transmission unit 16 that generates information indicating which of the first port 11 or the second port 12 is the gateway device based on the determination result by the disconnection determination unit 15 and transmits it to the device 50. Further, at least one of the devices 50 is composed of an operator 60 including a reception unit 61 that receives the information transmitted from the transmission unit 16 and an access unit 62 that transmits an access request to the general-purpose controller 1c to the gateway device indicated by the information received by the reception unit 61. The general-purpose controller 1c receives the access request transmitted from the access unit 62 via the gateway device. Thereby, the general-purpose controller 1c can notify the device 50 which of the first port 11 or the second port 12 is the gateway device. Further, even when the gateway device indicated by the gateway device information changes, the operator 60 can appropriately switch the access path to the general-purpose controller 1c according to the change and continue operating even when a disconnection occurs in the serial communication line 30.

[0078] In addition, the access unit 62 transmits an access request for the integrated controller 80 connected to the general-purpose controller 1c via a communication line 70 different from the serial communication line 30 to the gateway device indicated by the information received by the receiving unit 61. The general-purpose controller 1c includes a transfer unit 19 that transfers the access request to the integrated controller 80 via a different communication line 70 when the access request transmitted to the gateway device is an access request for the integrated controller 80. Thereby, the general-purpose controller 1c can appropriately transfer an access request from the operator 60 to the integrated controller 80 to the integrated controller 80.

[0079] Embodiment 4. In Embodiments 1 to 3, an example of redundantizing the path of the network configured by the serial communication line 30 has been described. In Embodiment 4, in addition to such path redundancy, an example of redundantizing (duplicating) the general-purpose controller itself will be described.

[0080] FIG. 15 is a diagram showing a configuration example of the redundant system 100 according to Embodiment 4. The redundant system 100 according to Embodiment 4 includes two general-purpose controllers 1d and 1e. These controllers are connected by serial communication lines 40 and 45. The general-purpose controllers 1d and 1e are connected to each other via the communication line 70 and are also connected to the integrated controller 80.

[0081] One of the general-purpose controllers 1d and 1e operates as an active system, and the other operates as a standby system. Here, for easy understanding, it is assumed that the general-purpose controller 1d operates as the active system and the general-purpose controller 1e operates as the standby system. The general-purpose controller 1d operating as the active system is referred to as the "active controller 1d", and the general-purpose controller 1e operating as the standby system is referred to as the "standby controller 1e". The holding information of the active controller 1d and the standby controller 1e is synchronized with each other via, for example, the communication line 70.

[0082] Also, the configuration examples of the active controller 1d and the standby controller 1e are the same as those of the general-purpose controller 1 according to Embodiment 1 shown in FIG. 2. Here, d or e is added to the name of each part shown in FIG. 2 to explain the configuration examples of the controllers 1d and 1e.

[0083] The active controller 1d includes a first port 11d, a second port 12d, a communication unit 13d (a state information acquisition unit 131d and a held information acquisition unit 132d), and a storage unit 14d.

[0084] The standby controller 1e includes a first port 11e, a second port 12e, a communication unit 13e (a state information acquisition unit 131e and a held information acquisition unit 132e), and a storage unit 14e.

[0085] As shown in FIG. 15, in the redundant system 100, one end of the serial communication line 30 (the first serial communication line) is connected to the first port 11d of the active controller 1d, and the other end of the serial communication line 30 is connected to the first port 11e of the standby controller 1e. That is, in the redundant system 100, the first ports of the mutual general-purpose controllers are connected by the serial communication line 30.

[0086] Also, the second port 12d of the active controller 1d and the second port 12e of the standby controller 1e are connected by a serial communication line 40 (the second serial communication line). Thereby, in the redundant system 100, a large ring-shaped network is configured by two controllers 1d and 1e, a secondary device 50, and the serial communication line 30 and the serial communication line 40.

[0087] The serial communication line 45 is a communication line used to confirm whether the two controllers 1d and 1e are operating normally. The serial communication line 45 connects the communication port of the active controller 1d and the communication port of the standby controller 1e. Each controller 1d and 1e checks whether the other is operating normally (whether an abnormality has occurred) via this serial communication line 45.

[0088] In the redundant system 100, serial addresses for the active controller 1d and the standby controller 1e are assigned as follows. That is, for the first port 11d (1CH) of the active controller 1d, the serial address "1". For the second port 12e (2CH) of the standby controller 1e, the serial address "0" is assigned. In addition, for the second port 12d (2CH) of the active controller 1d, the serial address "127" is assigned, and for the first port 11e (1CH) of the standby controller 1e, the serial address "126" is assigned. In this way, different addresses are assigned to each channel for the two controllers. Note that the active controller 1d has two channels (1CH and 2CH) as described above, and each channel has two crossover connectors, and these two connectors are physically bridge-connected inside the device. Similarly, the standby controller 1e also has two crossover connectors for each channel, and these two connectors are physically bridge-connected inside the device. Also, for the secondary device 50, similar to the first embodiment, serial addresses 「2」 ~ 「125」 are assigned in advance by an engineer according to the daisy-chain arrangement.

[0089] And in the redundant system 100, the first direction around and the second direction around as seen from the active controller 1d are as follows. That is, from the first port 11d of the active controller 1d, the direction towards the first port 11e of the standby controller 1e, the second port 12e of the standby controller 1e, and through the serial communication line 40 to the second port 12d of the active controller 1d is the first direction around (symbol P in FIG. 15).

[0090] Conversely, from the second port 12d of the active controller 1d, the direction towards the first port 11d of the active controller 1d through the serial communication line 40, the second port 12e of the standby controller 1e, and the first port 11e of the standby controller 1e is the second direction around (symbol Q in FIG. 15). Note that although the standby controller 1e is operating as a standby, information can be transmitted and received between it and the active controller 1d.

[0091] In the redundant system 100, normally, as described above, the active controller 1d operates as the active system. In this case, the communication unit (active system side communication unit) 13d of the active controller 1d accesses the device 50 around the first direction or the second direction, and performs serial communication with the device 50. Here, when any abnormality occurs in the active controller 1d, the active controller 1d notifies the standby controller 1e of the occurrence of the abnormality in itself via the serial communication line 45.

[0092] Upon receiving this notification, the standby controller 1e quickly switches from the standby system to the active system and thereafter operates as the active system. That is, the communication unit (standby system side communication unit) 13e of the standby controller 1e accesses the device 50 around the second direction (reference symbol Q in FIG. 15) from the first port 11e of its own device, via the first port 11d of the active controller 1d, the second port 12d of the active controller 1d, and the serial communication line 40, toward the second port 12e of its own device, or around the first direction (reference symbol P in FIG. 15) from the second port 12e of its own device, via the serial communication line 40, the second port 12d of the active controller 1d, and the first port 11d of the active controller 1d, toward the first port 11e of its own device, and performs serial communication with the device 50. Thereby, in the redundant system 100d, even when an abnormality occurs in the active controller 1d, the operation of the entire system can be continued, and the reliability of the system is improved.

[0093] Note that the redundant system 100 according to Embodiment 4 is an application of the duplication technology employed in a conventional heat source controller to a general-purpose controller. The heat source controller is a controller for controlling heat source equipment in particular. For example, as shown in FIG. 16, the active heat source controller 200a and the standby heat source controller 200b are connected by an I / O module 250 for high-speed communication via Ethernet, and thus it is a controller that can be duplicated.

[0094] The redundant system 100 according to Embodiment 4 applies the concept of the duplication technology of this heat source controller to a general-purpose controller. However, in the redundant system 100 according to Embodiment 4, by connecting the duplicated general-purpose controllers 1d and 1e with the serial communication line 40, it is possible to realize the duplication function with a cheaper configuration without adding devices such as the I / O module 250 for high-speed communication.

[0095] As described above, according to Embodiment 4, the redundant system 100 includes an active controller 1d, a standby controller 1e, and one or more devices 50 connected to the serial communication line 30. The active controller 1d includes a first port 11d to which one end of the serial communication line 30 is connected, and a second port 12d to which one end of a serial communication line 40 different from the serial communication line 30 is connected. The standby controller 1e includes a first port 11e to which the other end of the serial communication line 30 is connected, and a second port 12e to which the other end of the serial communication line 40 is connected. The active controller 1d accesses the device 50 in a first direction around from the first port 11d of its own device, through the first port 11e of the standby controller 1e, the second port 12e of the standby controller 1e, and the serial communication line 40, toward the second port 12d of its own device, or in a second direction around from the second port 12d of its own device, through the serial communication line 40, the second port 12e of the standby controller 1e, and the first port 11e of the standby controller 1e, toward the first port 11d of its own device, and includes an active-side communication unit 13d capable of serial communication with the device 50. The standby controller 1e accesses the device 50 in a second direction around from the first port 11e of its own device, through the first port 11d of the active controller 1d, the second port 12d of the active controller 1d, and the serial communication line 40, toward the second port 12e of its own device, or in a first direction around from the second port 12e of its own device, through the serial communication line 40, the second port 12d of the active controller 1d, and the first port 11d of the active controller 1d, toward the first port 11e of its own device, and includes a standby-side communication unit 13e capable of serial communication with the device 50. Thereby, the redundant system 100 can make the path of the network constituted by the serial communication lines 30 and 40 redundant, and even when an abnormality occurs in the active controller 1d, the operation of the entire system can be continued, improving the reliability of the system.

[0096] In addition, within the scope of the invention of the present application, free combinations of each embodiment, modifications of any component of each embodiment, or omissions of any component in each embodiment are possible. For example, with respect to the redundant system according to Embodiment 4, the configurations described in Embodiment 2 and Embodiment 3 may be combined.

Explanation of Reference Numerals

[0097] 1, 1b, 1c General-purpose controller (first controller) 1d General-purpose controller (active system controller) 1e General-purpose controller (standby system controller) 11, 11d, 11e First port 12, 12d, 12e Second port 13 Communication unit 13d Active system side communication unit 13e Standby system side communication unit 14 Storage unit 15 Disconnection determination unit 16 Transmission unit 17 Reception unit 18 Response unit 19 Transfer unit 30, 40, 45 Serial communication line 50 Secondary device 60 Operator 61 Reception unit 62 Access unit 63 Storage unit 64 Display unit 70 Communication line 80 Integrated controller (second controller) 100 Redundant system 131 State information acquisition unit 132 Retained information acquisition unit P Around the first direction Q Around the second direction

Claims

1. a first controller; one or more devices daisy-chain connected to the first controller in a ring shape by a serial communication line, the first controller includes: a first port to which one end of the serial communication line is connected; a second port to which the other end of the serial communication line is connected; a communication unit capable of accessing the device in a first direction around from the first port to the second port or in a second direction around from the second port to the first port for serial communication; and is provided with: the communication unit includes a status information acquisition unit that acquires status information of the device by serial communication; the status information acquisition unit: as a result of sequentially accessing the devices in either one of the first direction around or the second direction around to acquire the status information of each device, if the status information cannot be acquired from any of the devices, switches the access direction to the other direction around of the first direction around or the second direction around and sequentially accesses the devices to acquire status information; the first controller includes: a disconnection determination unit that determines whether a disconnection has occurred in the serial communication line based on the acquisition result of the status information by the status information acquisition unit; the disconnection determination unit: when the acquisition result of the status information when the status information acquisition unit accesses in either one of the first direction around or the second direction around is reversed from the acquisition result when accessing in the other direction around, and when the reversed acquisition result is continuously obtained a predetermined number of times, it is determined that a disconnection has occurred in the serial communication line. A redundant system characterized by this.

2. A first controller; One or more devices daisy-chain connected to the first controller via a serial communication line, The first controller, A first port to which one end of the serial communication line is connected, A second port to which the other end of the serial communication line is connected, A communication unit capable of serial communication by accessing the device in a first direction around from the first port to the second port or in a second direction around from the second port to the first port, Comprising, The communication unit includes a state information acquisition unit that acquires state information of the device by serial communication, The state information acquisition unit, As a result of sequentially accessing the devices in either one of the first direction around or the second direction around and acquiring the state information of each device, if the state information cannot be acquired from any device, It switches the access direction to the other direction around of the first direction around or the second direction around and sequentially accesses the devices to acquire state information, The first controller, Based on the acquisition result of the state information by the state information acquisition unit, it includes a disconnection determination unit that determines whether a disconnection has occurred in the serial communication line, The disconnection determination unit, When the duration of the state where the state information acquisition unit fails to acquire the state information regardless of whether it accesses in the first direction around or the second direction around is equal to or longer than a predetermined time, and there are a predetermined number or more of the same devices with such a duration, it is determined that a plurality of disconnections have occurred in the serial communication line. A redundant system characterized by this.

3. A first controller, One or more devices daisy-chain connected to the first controller via a serial communication line, The first controller is, a first port to which one end of the serial communication line is connected, a second port to which the other end of the serial communication line is connected, a communication unit capable of accessing the device in a first direction around from the first port to the second port or in a second direction around from the second port to the first port for serial communication, and includes the communication unit includes a state information acquisition unit that acquires state information of the device by serial communication, the state information acquisition unit as a result of sequentially accessing the device in either one of the first direction around or the second direction around and acquiring the state information of each device, if the state information cannot be acquired from any device, switches the access direction to the other direction around of the first direction around or the second direction around and sequentially accesses the device to acquire the state information, the first controller includes a disconnection determination unit that determines whether a disconnection has occurred in the serial communication line based on the acquisition result of the state information by the state information acquisition unit, the first controller includes a transmission unit that generates information indicating which port of the first port or the second port is the gateway device based on the determination result by the disconnection determination unit and transmits the generated information to the device, at least one of the devices includes a reception unit that receives the information transmitted from the transmission unit, and an access unit that transmits an access request to the first controller to the gateway device indicated by the information received by the reception unit, and is configured by an operating device, the first controller A redundant system, characterized in that it receives an access request transmitted from the access unit via the gateway device.

4. The access unit of the operator transmits an access request for a second controller connected to the first controller via a communication line different from the serial communication line to the gateway device indicated by the information received by the receiving unit, The first controller The redundant system according to claim 3, characterized in that it comprises a transfer unit that transfers the access request to the second controller via the different communication line when the access request transmitted to the gateway device is an access request for the second controller.

5. A redundant system comprising an active controller, a standby controller, and one or more devices connected to a first serial communication line. The active controller comprises a first port to which one end of the first serial communication line is connected, and a second port to which one end of a second serial communication line different from the first serial communication line is connected. The standby controller comprises a first port to which the other end of the first serial communication line is connected, and a second port to which the other end of the second serial communication line is connected. The active controller From the first port of the own device, around the first direction towards the second port of the own device via the first port of the controller of the standby system, the second port of the controller of the standby system, and the second serial communication line, or around the second direction towards the first port of the own device via the second serial communication line, the second port of the controller of the standby system, and the first port of the controller of the standby system, access the device, and include an active system side communication unit capable of serial communication with the device. The controller of the standby system From the first port of the own device, around the second direction towards the second port of the own device via the first port of the controller of the active system, the second port of the controller of the active system, and the second serial communication line, or around the first direction towards the first port of the own device via the second serial communication line, the second port of the controller of the active system, and the first port of the controller of the active system, access the device, and include a standby system side communication unit capable of serial communication with the device. The active system side communication unit and the standby system side communication unit include a state information acquisition unit that acquires the state information of the device by serial communication. The state information acquisition unit included in the active system side communication unit and the state information acquisition unit included in the standby system side communication unit As a result of sequentially accessing the device around either the first direction or the second direction to acquire the state information of each device, if the state information cannot be acquired from any device, Switch the access direction to the other direction among the first direction and the second direction and sequentially access the device to acquire the state information. The controller of the active system Include a disconnection determination unit that determines whether a disconnection has occurred in the first serial communication line based on the acquisition result of the state information by the state information acquisition unit included in the active system side communication unit. The controller of the standby system A disconnection determination unit is provided to determine whether a disconnection has occurred in the first serial communication line based on the acquisition result of the state information by the state information acquisition unit included in the standby system side communication unit. The disconnection determination unit included in the controller of the active system is When the acquisition result of the state information when the state information acquisition unit included in the active system side communication unit accesses in either one of the first direction or the second direction is reversed from the acquisition result of the state information when accessing in the other direction, and when the reversed acquisition results are continuously obtained a predetermined number of times, it is determined that a disconnection has occurred in the first serial communication line. The disconnection determination unit included in the controller of the standby system is A redundant system, wherein when the acquisition result of the state information when the state information acquisition unit included in the standby system side communication unit accesses in either one of the first direction or the second direction is reversed from the acquisition result of the state information when accessing in the other direction, and when the reversed acquisition results are continuously obtained a predetermined number of times, it is determined that a disconnection has occurred in the first serial communication line.

6. It is configured to include a controller of the active system, a controller of the standby system, and one or more devices connected to the first serial communication line. The controller of the active system is A first port to which one end of the first serial communication line is connected, A second port to which one end of a second serial communication line different from the first serial communication line is connected. The controller of the standby system is A first port to which the other end of the first serial communication line is connected, A second port to which the other end of the second serial communication line is connected. The controller of the active system is From the first port of the own device, around a first direction towards the second port of the own device via the first port of the controller of the standby system, the second port of the controller of the standby system, and the second serial communication line, or around a second direction towards the first port of the own device via the second serial communication line, the second port of the controller of the standby system, and the first port of the controller of the standby system, access the device, and include an active system side communication unit capable of serial communication with the device. The controller of the standby system From the first port of the own device, around a second direction towards the second port of the own device via the first port of the controller of the active system, the second port of the controller of the active system, and the second serial communication line, or around a first direction towards the first port of the own device via the second serial communication line, the second port of the controller of the active system, and the first port of the controller of the active system, access the device, and include a standby system side communication unit capable of serial communication with the device. The active system side communication unit and the standby system side communication unit include a state information acquisition unit that acquires state information of the device by serial communication. The state information acquisition unit included in the active system side communication unit and the state information acquisition unit included in the standby system side communication unit As a result of sequentially accessing the device around either the first direction or the second direction and acquiring the state information of each device, if the state information cannot be acquired from any device, Switch the access direction to the other direction of the first direction or the second direction and sequentially access the device to acquire the state information. The controller of the active system Include a disconnection determination unit that determines whether a disconnection has occurred in the first serial communication line based on the acquisition result of the state information by the state information acquisition unit included in the active system side communication unit. The controller of the standby system A disconnection determination unit that determines whether a disconnection has occurred in the first serial communication line based on the acquisition result of the status information by the status information acquisition unit included in the standby system side communication unit. The disconnection determination unit included in the controller of the active system is When the duration of the state where the status information acquisition unit included in the active system side communication unit fails to acquire the status information regardless of whether it accesses in either the first direction or the second direction is equal to or longer than a predetermined time, and there are a predetermined number or more of the same devices with such a duration, it is determined that a plurality of disconnections have occurred in the first serial communication line. The disconnection determination unit included in the controller of the standby system is A redundant system characterized in that when the duration of the state where the status information acquisition unit included in the standby system side communication unit fails to acquire the status information regardless of whether it accesses in either the first direction or the second direction is equal to or longer than a predetermined time, and there are a predetermined number or more of the same devices with such a duration, it is determined that a plurality of disconnections have occurred in the first serial communication line.

7. A first port to which one end of a serial communication line to which one or more devices are daisy-chain connected in a ring shape is connected, A second port to which the other end of the serial communication line is connected, A communication unit capable of serial communication by accessing the device in a first direction from the first port to the second port or in a second direction from the second port to the first port, is provided, The communication unit includes a status information acquisition unit that acquires the status information of the device by serial communication, The status information acquisition unit is As a result of sequentially accessing the devices in either the first direction or the second direction among the first direction and the second direction to acquire the status information of each device, if the status information cannot be acquired from any device, It sequentially accesses the device by switching the access direction to the other direction around the first direction or the second direction, and acquires status information. It includes a disconnection determination unit that determines whether a disconnection has occurred in the serial communication line based on the acquisition result of the status information by the status information acquisition unit. The disconnection determination unit When the acquisition result of the status information when the status information acquisition unit accesses around either the first direction or the second direction is reversed from the acquisition result of the status information when accessing around the other direction, and when the reversed acquisition result is continuously obtained a predetermined number of times, it determines that a disconnection has occurred in the serial communication line. A controller characterized by this.

8. A first port to which one end of a serial communication line to which one or more devices are daisy-chain connected in a ring shape is connected, A second port to which the other end of the serial communication line is connected, A communication unit capable of serial communication that accesses the device in a first direction from the first port to the second port or in a second direction from the second port to the first port, Comprising The communication unit includes a status information acquisition unit that acquires the status information of the device by serial communication. The status information acquisition unit As a result of sequentially accessing the device in either the first direction or the second direction and acquiring the status information of each device, if the status information could not be acquired from any device, It sequentially accesses the device by switching the access direction to the other direction around the first direction or the second direction, and acquires status information. It includes a disconnection determination unit that determines whether a disconnection has occurred in the serial communication line based on the acquisition result of the status information by the status information acquisition unit. The disconnection determination unit When the duration of the state where the state information acquisition unit fails to acquire state information regardless of whether it accesses around the first direction or the second direction is equal to or longer than a predetermined time, and when there are a predetermined number or more of the same devices with the same duration, it is determined that a plurality of disconnections have occurred in the serial communication line. A controller characterized by this.

Images