Communication device, communication system, communication control method and program

Abstract

A communication device (1) is a communication device to which a plurality of slaves (2) are daisy-chain connected, and which communicates with the plurality of slaves (2). The communication device (1) is provided with a processing unit (111). The processing unit (111) executes setting processing. In the setting processing, an update period of a specific slave (2) which is the slave, from among the plurality of slaves (2), having the shortest data update period, is set as a reference period, and the update periods of the other slaves (2) from among the plurality of slaves (2), other than the specific slave (2), are each set to an integral multiple of the reference period.

Description

[Technical Field]

[0001] The present disclosure generally relates to a communication device, a communication system, a communication control method, and a program, and more particularly to a communication device, a communication system, a communication control method, and a program that communicate with multiple slaves. [Background technology]

[0002] Patent Document 1 describes a data transmission system (communication system) that uses a cyclic transmission frame structure. The data transmission system described in Patent Document 1 includes a control sequencer (communication device) and a controlled drive device (slave). The control sequencer and the controlled drive device are connected to each other via a data transmission line.

[0003] In the data transmission system described in Patent Document 1, data frames containing data requiring high-speed communication and data that can be communicated at low speed are cyclically transmitted. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-244218 Summary of the Invention

[0005] In the data transmission system described in Patent Document 1, for example, when multiple controlled drives with different data update cycles are daisy-chained to a control sequencer, the communication cycle is adjusted to that of the controlled drive with the shortest update cycle, which results in an over-spec for controlled drives with long update cycles, resulting in a problem of reduced communication efficiency.

[0006] An object of the present disclosure is to provide a communication device, a communication system, a communication control method, and a program that can improve communication efficiency.

[0007] A communication device according to one aspect of the present disclosure is a communication device that communicates with a plurality of slaves daisy-chained together. The communication device includes a processing unit. The processing unit executes a setting process. In the setting process, the update period of a specific slave, which is one of the plurality of slaves and has the shortest data update period, is set to a reference period, and the update periods of other slaves, different from the specific slave, are set to integer multiples of the reference period.

[0008] A communication system according to another aspect of the present disclosure includes the above-described communication device and a plurality of slaves, the plurality of slaves being connected to the communication device and communicating with the communication device.

[0009] According to another aspect of the present disclosure, there is provided a communication control method for use in a communication device that communicates with a plurality of slaves connected in a daisy chain, the communication control method including a setting step, in which the update period of a specific slave that has the shortest data update period among the plurality of slaves is set to a reference period, and the update periods of other slaves different from the specific slave are set to an integer multiple of the reference period.

[0010] A program according to another aspect of the present disclosure is a program for causing one or more processors to execute the above-described communication control method.

[0011] According to the communication device, communication system, communication control method, and program according to the above aspects of the present disclosure, it is possible to improve communication efficiency. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a block diagram showing an overview of a communication system including a communication device according to an embodiment. [Figure 2] FIG. 2 is a diagram showing an example of a frame in the communication system. [Figure 3] FIG. 3 is an explanatory diagram of the update period of each slave in the communication system and the data field of a frame transmitted from a communication device. [Figure 4] FIG. 4 is an explanatory diagram of the operation timing of the communication system. [Figure 5] FIG. 5 is a flowchart showing the operation of the communication device in the communication system. [Figure 6] FIG. 6 is a flowchart showing the operation of each slave in the communication system. [Figure 7] FIG. 7 is an explanatory diagram of the update period of each slave in the communication system according to the first modification of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] (1) Overview Fig. 1 is a block diagram showing an overview of a communication system 100 including a communication device 1 according to an embodiment. Fig. 3 is an explanatory diagram of the update period of each slave in the communication system 100 and the data field of a frame transmitted from the communication device 1.

[0014] As shown in FIG. 1, a communication device 1 according to this embodiment configures a communication system 100 together with a plurality of (e.g., five) slaves 2 connected to the communication device 1. In other words, the communication device 1 is a master that corresponds to a higher-level device of the plurality of slaves 2. The communication device 1 and the plurality of slaves 2 are connected to the same network. In other words, the communication system 100 includes the communication device 1 and the plurality of slaves 2. The plurality of slaves 2 are connected to the communication device 1 and communicate with the communication device 1.

[0015] In this embodiment, the communication device 1 and the multiple slaves 2 are connected to an industrial network. In this disclosure, the "industrial network" refers to, for example, a field network used in factory automation, which is used for communication between multiple devices installed in a factory. The industrial network may include, for example, Ethernet / IP (registered trademark), EtherCAT (registered trademark), or PROFINET (registered trademark). The devices connected to the industrial network may include, for example, a controller (for example, a programmable logic controller (PLC)), a sensor (for example, a displacement sensor, a flow meter, a pressure gauge, or an image sensor), or a remote I / O (input / output). The devices connected to the industrial network may also include, for example, a servo amplifier, an inverter, a robot, an actuator, or a valve.

[0016] Industrial networks are required to be more robust, punctual, and real-time than standard best-effort networks used in offices, etc. For example, in an industrial network, when periodically sending control data from a controller to a controlled device such as a servo amplifier, delays are not tolerated as much as in a best-effort network, and faster response speeds to the control data are also required.

[0017] A communication device 1 according to this embodiment is a communication device that has a plurality of slaves 2 daisy-chained together and communicates with the plurality of slaves 2. As shown in Fig. 1, the communication device 1 includes a processing unit 111. The processing unit 111 executes a setting process.

[0018] The setting process is a process for setting the update period CT1 (see FIG. 3) of each of the multiple slaves 2. That is, the communication device 1 sets the update period CT1 of each of the multiple slaves 2 by executing the setting process. More specifically, in the setting process, the update period CT1 of a specific slave 2 (here, a first slave 21 and a second slave 22 described below), which is the slave with the shortest data update period CT1 among the multiple slaves 2, is set to the reference period CT0 (see FIG. 3). Also, in the setting process, the update periods CT1 of other slaves 2 (here, a third slave 23, a fourth slave 24, and a fifth slave 25 described below) other than the specific slave 2 among the multiple slaves 2 are set to integer multiples of the reference period CT0.

[0019] As described above, in the communication device 1 according to this embodiment, the update period CT1 of a specific slave 2 is set to the reference period CT0, and the update periods CT1 of the other slaves 2 are set to an integer multiple of the reference period CT0. This prevents the other slaves 2 from becoming over-specified, and makes it possible to improve communication efficiency. Furthermore, it becomes possible to set different update periods CT1 for a specific slave 2 that requires relatively high-speed control and for other slaves 2 that do not require relatively high-speed control, thereby making it possible to improve the efficiency of the calculation processing of the communication device 1.

[0020] (2) Details A communication system 100 including a communication device 1 according to this embodiment will be described in detail below with reference to FIG. 1. FIG. 1 is a block diagram showing an overview of the communication system 100 including the communication device 1 according to this embodiment. In this embodiment, a plurality of (e.g., five) slaves 2 are connected to the communication device 1. Furthermore, in this embodiment, the plurality of slaves 2 are daisy-chained to the communication device 1. Specifically, a first slave 21, a second slave 22, a third slave 23, a fourth slave 24, and a fifth slave 25 are connected to the communication device 1 in this order in a ring shape. Therefore, in this embodiment, a frame F1 transmitted from the communication device 1 is transmitted in the order of the first slave 21, the second slave 22, the third slave 23, the fourth slave 24, the fifth slave 25, and the communication device 1.

[0021] Moreover, in the communication system 100 according to this embodiment, of the multiple (five) slaves 2, two slaves 2 are servo amplifiers and three slaves 2 are sensors. Specifically, the first slave 21 and the second slave 22 are servo amplifiers, and the third slave 23, the fourth slave 24, and the fifth slave 25 are sensors. Moreover, in the communication system 100 according to this embodiment, the communication device 1 is a controller that controls the multiple slaves 2 (that is, the multiple servo amplifiers and sensors) individually or collectively.

[0022] (2.1) Communication equipment 1, the communication device 1 includes a control unit 11 and a communication unit 12. In this embodiment, the communication device 1 stores data in a memory included in the control unit 11, but may also include a storage unit separate from the control unit 11. Examples of the storage unit include electrically rewritable nonvolatile memory such as an EEPROM (Electrically Erasable Programmable Read-Only Memory) and volatile memory such as a RAM (Random Access Memory).

[0023] The control unit 11 includes, for example, a computer system. The computer system is mainly composed of a processor and a memory as hardware. The processor executes a program recorded in the memory of the computer system, thereby realizing the functions of the control unit 11 (including a processing unit 111 and a calculation unit 112 described below). The program may be pre-recorded in the memory of the computer system, provided via a telecommunications line, or provided by being recorded on a non-transitory recording medium such as a memory card, optical disk, or hard disk drive that is readable by the computer system.

[0024] The communication unit 12 is a communication interface for communicating with a plurality of slaves 2. The communication unit 12 has, for example, a wired communication module that complies with the industrial Ethernet (registered trademark) protocol. The communication unit 12 transmits a frame F1 to a communication unit 202 (described later) of a slave 2 (first slave 21 in FIG. 1) that is directly connected to the communication device 1 and located at the front stage. The communication unit 12 also receives a frame F1 transmitted from a communication unit 202 of a slave 2 (fifth slave 25 in FIG. 1) that is directly connected to the communication device 1 and located at the last stage.

[0025] 1, the control unit 11 includes a processing unit 111 and a calculation unit 112. In other words, the communication device 1 includes the processing unit 111 and the calculation unit 112.

[0026] The processing unit 111 has a function to execute a communication process and a setting process, and further has a function to execute a calculation process.

[0027] The communication process is a process in which the communication unit 12 transmits a frame F1 to a plurality of slaves 2 at a reference period CT0 (see FIG. 3). As will be described later, the reference period CT0 is set based on the update period CT1 (see FIG. 3) of the plurality of slaves 2. In this embodiment, when the communication device 1 transmits the frame F1 to the first slave 21, the frame F1 is transmitted in the order of the first slave 21, the second slave 22, the third slave 23, the fourth slave 24, and the fifth slave 25 (see FIG. 1).

[0028] Next, the frame F1 will be described. Fig. 2 is a configuration diagram showing an example of the frame F1 in the communication system 100 of this embodiment. As shown in Fig. 2, the frame F1 includes a header D100, a data area D1, a result D101, and a cyclic redundancy check (CRC) D102. The data area D1 is an area (slot) used for transmitting data from the communication device 1 to each slave 2, and data from each slave 2 to the communication device 1. In other words, data from the communication device 1 to each slave 2, and data from each slave 2 to the communication device 1 are transmitted in the data area D1.

[0029] The data region D1 includes a plurality of slots. In the example shown in FIG. 2, the data region D1 includes four slots: D11, D12, D13, and D0. The slot D11 is a slot for storing data from the communication device 1 to the first slave 21 and data from the first slave 21 to the communication device 1. The slot D12 is a slot for storing data from the communication device 1 to the second slave 22 and data from the second slave 22 to the communication device 1. The slot D13 is a slot for storing data from the communication device 1 to the third slave 23 and data from the third slave 23 to the communication device 1. The slot D0 is a slot for storing unused data, which will be described later. That is, in the example shown in FIG. 2, the frame F1 can transmit data from the first slave 21, the second slave 22, and the third slave 23.

[0030] The slave 2 that receives the frame F1 can acquire data from the communication device 1 using the slot assigned to it in the data region D1. In the example shown in FIG. 2, the first slave 21 can acquire data from the communication device 1 using slot D11 in the data region D1. The second slave 22 can acquire data from the communication device 1 using slot D12 in the data region D1. The third slave 23 can acquire data from the communication device 1 using slot D13 in the data region D1. Note that in the example shown in FIG. 2, slot D14 (see FIG. 3) corresponding to the fourth slave 24 and slot D15 (see FIG. 3) corresponding to the fifth slave 25 are not included in the frame F1. Therefore, the fourth slave 24 and the fifth slave 25 cannot receive data from the communication device 1 even if the frame F1 shown in FIG. 2 is sent.

[0031] In this embodiment, data transmitted in the communication system 100 may include control data for each slave 2, which is transmitted from the communication device 1 to each slave 2. Furthermore, data transmitted in the communication system 100 may include response data in response to the control data for each slave 2, which is transmitted from each slave 2 to the communication device 1.

[0032] In this embodiment, the processing unit 111 updates data at every reference period CT0. The processing unit 111 generates data to be included in the next frame F1 during the period from when the transmission of the frame F1 starts until the transmission of the next frame F1 starts. When generating data, the processing unit 111 refers to, for example, command information from a higher-level system of the communication device 1 and response information received from each slave 2. For example, the processing unit 111 generates control data for controlling the servo amplifiers (the first slave 21 and the second slave 22) by referring to detection information received from sensors (the third slave 23, the fourth slave 24, and the fifth slave 25). Therefore, the reference period CT0 needs to be set to a value that allows the processing unit 111 to execute the process of generating data, and depends on the processing capacity of the processing unit 111.

[0033] The setting process is a process for setting the reference period CT0 used in the communication process and the update period CT1 of each slave 2. That is, the communication process is executed based on the parameters set in the setting process.

[0034] In the setting process, the processing unit 111 sets the update period CT1 of a specific slave 2, which has the shortest data update period CT1 among the multiple slaves 2, to the reference period CT0. Also, in the setting process, the processing unit 111 sets the update periods CT1 of other slaves 2, which are different from the specific slave 2, among the multiple slaves 2, to an integer multiple of the reference period CT0. This setting method will be explained using Figure 3. Figure 3 is an explanatory diagram of the update periods of each slave 2 in the communication system 100 of this embodiment, and the data field of the frame F1 transmitted from the communication device 1.

[0035] Specifically, in the setting process, the processing unit 111 sets the update period CT11 of the first slave 21 and the update period CT12 of the second slave 22, which have the shortest data update period CT1, as the reference period CT0, as shown in FIG. 3. Also, in the setting process, the processing unit 111 sets the update period CT13 of the third slave 23, which is longer than the update period CT11 of the first slave 21 and the update period CT12 of the second slave 22, to twice the reference period CT0, as shown in FIG. 3. Also, in the setting process, the processing unit 111 sets the update period CT14 of the fourth slave 24 and the update period CT15 of the fifth slave 25, which are longer than the update period CT13 of the third slave 23, to three times the reference period CT0, as shown in FIG. 3. Each of the update periods CT11, CT12, and the reference period CT0 is, for example, 1 ms. Therefore, in this embodiment, the update period CT13 is 2 ms, and both the update periods CT14 and CT15 are 3 ms.

[0036] The calculation process is a process for calculating an adjustment value for synchronizing the communication device 1 and the multiple slaves 2. In the calculation process, the processing unit 111 calculates the sum of a first time and a second time as the adjustment value. The first time is the processing time from when each of the multiple slaves 2 receives a frame F1 from the communication device 1 or slave 2 directly connected to the previous slave 2 until it generates a predetermined pulse. The predetermined pulse is, for example, a synchronization pulse. The second time is the product of a difference between the number of the multiple slaves 2 and the order of connection from the communication device 1 to each of the multiple slaves 2, and a fixed delay value. The fixed delay value is the sum of the delay amount of the PHY (physical layer) constituting each slave 2, the delay amount of the wiring between the communication device 1 or an adjacent slave 2, and the internal processing time of each slave 2. Here, the delay amount of the wiring is sufficiently smaller than the delay amount of the PHY, so the fixed delay value may be the sum of the delay amount of the PHY and the internal processing time of each slave 2. Details of the calculation process will be described in the section “(4) Calculation Process.”

[0037] The calculation unit 112 calculates the maximum number of transmitters. In the present disclosure, the "maximum number of transmitters" is the maximum number of slaves 2 that can transmit data in frames F1 transmitted from the communication device 1 for each reference period CT0, among the multiple slaves 2. Details of the process by which the calculation unit 112 calculates the maximum number of transmitters will be described in the section "(3) Calculation of the maximum number of transmitters."

[0038] In this embodiment, the processing unit 111 compares the number of slaves 2 corresponding to the data included in frame F1 with the maximum number of transmissions in each reference cycle CT0. If the number of slaves 2 is the same as the maximum number of transmissions, the processing unit 111 outputs frame F1 to the communication unit 12 as is. On the other hand, if the number of slaves 2 is less than the maximum number of transmissions, the processing unit 111 adds unused data to frame F1 and outputs frame F1 with the added unused data to the communication unit 12. In this disclosure, "unused data" refers to data that is not used in communication between the communication device 1 and multiple slaves 2. In this embodiment, the processing unit 111 adds "0" as unused data, but the unused data may be any data that is not used in communication between the communication device 1 and multiple slaves 2, and is not limited to "0".

[0039] In this way, by adding unused data when the number of slaves 2 is less than the maximum number of transmission devices, it is possible to equalize the frame length of the frame F1 in each reference period CT0, and as a result, it is possible to synchronize the communication device 1 with the multiple slaves 2. In short, the processing unit 111 synchronizes the communication device 1 with the multiple slaves 2 by adding unused data to the frame F1.

[0040] (2.2) Slave 1, each of the plurality of slaves 2 includes a processing unit 201 and a communication unit 202. In this embodiment, each of the plurality of slaves 2 stores data in a memory included in the processing unit 201, but may also include a storage unit separate from the processing unit 201. Examples of the storage unit include electrically rewritable nonvolatile memory such as an EEPROM, and volatile memory such as a RAM.

[0041] The processing unit 201 includes, for example, a computer system. The computer system is mainly composed of a processor and a memory as hardware. The functions of the processing unit 201 are realized by the processor executing a program recorded in the memory of the computer system. The program may be pre-recorded in the memory of the computer system, may be provided via a telecommunications line, or may be provided by being recorded on a non-transitory recording medium such as a memory card, an optical disk, or a hard disk drive that is readable by the computer system.

[0042] The processing unit 201 executes processing based on corresponding data among the multiple pieces of data included in the frame F1 received by the communication unit 202. Furthermore, as will be described later, when an area for storing device-to-device data is included in the frame F1, the processing unit 201 may have a function of executing processing to transmit the device-to-device data to another slave 2 using the area.

[0043] The communication unit 202 is a communication interface for communicating with the communication device 1 or another slave 2. The communication unit 202 includes, for example, a wired communication module conforming to the Industrial Ethernet (registered trademark) protocol. The communication unit 202 receives a frame F1 transmitted from the communication unit 12 of the communication device 1 or the communication unit 202 of the slave 2, which is located in a preceding stage and directly connected to the slave 2. The communication unit 202 also transmits the received frame F1 to the communication unit 12 of the communication device 1 or the communication unit 202 of the slave 2, which is located in a subsequent stage and directly connected to the slave 2. As an example, the communication unit 202 of the first slave 21 receives the frame F1 transmitted from the communication unit 12 of the communication device 1 and transmits the received frame F1 to the communication unit 202 of the second slave 22. At this time, the communication unit 202 of the first slave 21 may appropriately update the received frame F1 before transmitting it. Furthermore, the communication unit 202 of the second slave 22 receives the frame F1 transmitted from the communication unit 202 of the first slave 21, and transmits the received frame F1 to the communication unit 202 of the third slave .

[0044] (3) Calculating the maximum number of transmitting devices Hereinafter, the calculation unit 112 calculates the value of maximum The process of calculating the number of transmitting devices will be described.

[0045] The calculation unit 112 calculates the maximum number of transmitters for each reference period CT0 based on the quotient and remainder obtained when the number of slaves 2 having the same update period CT1 is divided by a set value. As described above, the maximum number of transmitters is the maximum number of slaves 2 among the multiple slaves 2 that can transmit data in frames F1 transmitted from the communication device 1 for each reference period CT0. Here, the set value is the magnification of the update period CT1 relative to the reference period CT0. Specifically, the set value for each of the first slave 21 and the second slave 22 is "1," the set value for the third slave 23 is "2," and the set value for each of the fourth slave 24 and the fifth slave 25 is "3."

[0046] When the calculation unit 112 divides the number of slaves 2 with the same update period CT1 by the set value, if the remainder is greater than "0", the calculation unit 112 sets the number of slaves 2 to be added to the maximum number of transmissions to "1", and if the remainder is less than or equal to "0", the calculation unit 112 sets the number of slaves 2 to be added to the maximum number of transmissions to "0". Furthermore, when the calculation unit 112 divides the number of slaves 2 with the same update period CT1 by the set value, the calculation unit 112 sets the obtained quotient as the number of slaves 2 to be added to the maximum number of transmissions.

[0047] For the first slave 21 and the second slave 22, which have the same update period CT1, the number of slaves 2 is "2" and the set value is "1", so the quotient is "2" and the remainder is "0". For the third slave 23, the number of slaves 2 is "1" and the set value is "2", so the quotient is "0" and the remainder is "1". For the fourth slave 24 and the fifth slave 25, which have the same update period CT1, the number of slaves 2 is "2" and the set value is "3", so the quotient is "0" and the remainder is "2". Therefore, the maximum number of transmission devices calculated by the calculation unit 112 is four (2 devices + 1 device + 1 device). For this reason, it is possible for the frame F1 transmitted from the communication device 1 to include data for a maximum of four slaves 2.

[0048] In short, the calculation unit 112 calculates the maximum number of transmission units according to the following function:

[0049] Function: Maximum number of transmissions = Σ [(Number of slaves at each update cycle CT1 / Setting value) Integer value + if {Remainder of (Number of slaves at each update cycle CT1 / Setting value) > 0 then 1 else 0}] Here, the symbol Σ indicates the sum of each update period CT1. Also, the "integer value of the quotient" refers to the value of the integer part of the quotient. For example, if the quotient is 2.5, the integer value of the quotient is 2. Also, for if and below, the value is 1 when the remainder of (number of slaves at each update period CT1 / setting value) is greater than 0, and the value is 0 when the remainder of (number of slaves at each update period CT1 / setting value) is 0.

[0050] As described above, the maximum number of transmitting devices is four, and therefore the data area D1 in each reference period CT0 includes four slots, as shown in Fig. 3. Details of the data area D1 in each reference period CT0 will be described below.

[0051] 3, in the first reference period CT0, the data region D1 includes a slot D11 corresponding to the first slave 21, a slot D12 corresponding to the second slave 22, and a slot D13 corresponding to the third slave 23. In addition, since data is only transmitted to three slaves 2 in the first reference period CT0, one slot D0 is added to the frame F1 to match the frame length with the subsequent frame F1. The unused data described above is stored in the slot D0.

[0052] 3, in the second reference period CT0, the data area D1 includes slot D11, slot D12, and slot D14 corresponding to the fourth slave 24. Also, in the second reference period CT0, one slot D0 is included in frame F1, as in the first reference period CT0. Here, because the update period CT13 of the third slave 23 is set to twice the reference period CT0, slot D13 is not included in the second reference period CT0.

[0053] 3, in the third reference period CT0, the data region D1 includes slots D11, D12, D13, and slot D15 corresponding to the fifth slave 25. Here, the update period CT14 of the fourth slave 24 is set to three times the reference period CT0, so slot D14 is not included in the third reference period CT0. Also, in the third reference period CT0, the data region D1 includes four slots D11, D12, D13, and D15 corresponding to the four slaves (maximum number of transmitters), the first slave 21, the second slave 22, the third slave 23, and the fifth slave 25, so slot D0 is not included in the data region D1.

[0054] 3, in the fourth reference period CT0, the data area D1 includes slots D11 and D12. Also, in the fourth reference period CT0, two slots D0 are added to frame F1. Here, the update period CT13 of the third slave 23 is set to twice the reference period CT0, and the update periods CT14 and CT15 of the fourth slave 24 and fifth slave 25 are set to three times the reference period CT0, so the fourth reference period CT0 does not include slots D13, D14, or D15.

[0055] 3, in the fifth reference period CT0, the data region D1 includes slots D11, D12, D13, and D14. Here, the update period CT15 of the fifth slave 25 is set to three times the reference period CT0, so slot D15 is not included in the fifth reference period CT0. Also, in the fifth reference period CT0, the data region D1 includes four slots D11, D12, D13, and D14 for the four slaves (maximum number of transmitters): the first slave 21, the second slave 22, the third slave 23, and the fourth slave 24, so slot D0 is not included in the data region D1.

[0056] 3, in the sixth reference period CT0, the data area D1 includes slots D11, D12, and D15. Also, in the sixth reference period CT0, one slot D0 is added to frame F1, as in the first reference period CT0. Here, the update period CT13 of the third slave 23 is set to twice the reference period CT0, and the update period CT14 of the fourth slave 24 is set to three times the reference period CT0, so the sixth reference period CT0 does not include slots D13 and D14.

[0057] Here, the update period CT14 of the fourth slave 24 and the update period CT15 of the fifth slave 25 are both set to three times the reference period CT0, but as shown in Fig. 3, the start timings of the update periods CT14 and CT15 are made to differ by the amount of the reference period CT0. That is, when the update periods CT1 of two or more slaves 2 out of the multiple slaves 2 are the same, the processing unit 111 makes the start timings of the update periods CT1 of the two or more slaves 2 differ by at least the amount of the reference period CT0. This makes it possible to reduce the amount of data transmitted in each reference period CT0 compared to when the start timings of the update periods CT14 and CT15 are the same, and as a result, it becomes possible to shorten the frame length of the frame F1.

[0058] (4) Calculation process (calculation of adjustment value) Next, the calculation process executed by the processing unit 111 of the communication device 1 will be described with reference to FIG. 4. FIG. 4 is an explanatory diagram of the operation timing of the communication system 100 of this embodiment. "Time T1" in FIG. 4 is a delay value that occurs when frame F1 is received, and is the sum of the PHY delay amount and the wiring delay amount. Also, "time T2" ​​in FIG. 4 is a delay value that occurs when frame F1 is transmitted, and is the internal processing time of each slave 2. In this embodiment, the sum of time T1 and time T2 becomes the fixed delay value. Also, "time T0" in FIG. 4 represents the first time shown below. A synchronization pulse P is generated at time T0 after each slave 2 receives frame F1.

[0059] As described above, the calculation process is a process for calculating an adjustment value (SYNC value) for synchronizing the communication device 1 and the multiple slaves 2. In the calculation process, the processing unit 111 calculates the adjustment value for the multiple slaves 2. Here, as described above, the adjustment value is the sum of the first time and the second time. The first time is the processing time from when each of the multiple slaves 2 receives a frame F1 from the communication device 1 or slave 2 directly connected to the previous slave 2 until it generates a synchronization pulse P. Furthermore, the second time is the product of the difference between the number of the multiple slaves 2 and the connection order from the communication device 1 for each of the multiple slaves 2, and the fixed delay value.

[0060] Since the number of slaves 2 is "5" and the connection order of the first slave 21 is "1", the adjustment value of the first slave 21 is {T0+4×(T1+T2)}. Furthermore, since the connection order of the second slave 22 is "2", the adjustment value of the second slave 22 is {T0+3×(T1+T2)}. Furthermore, since the connection order of the third slave 23 is "3", the adjustment value of the third slave 23 is {T0+2×(T1+T2)}. Furthermore, since the connection order of the fourth slave 24 is "4", the adjustment value of the fourth slave 24 is {T0+(T1+T2)}. Furthermore, since the connection order of the fifth slave 25 is "5", the adjustment value of the fifth slave 25 is T0.

[0061] Thus, in the communication system 100 according to this embodiment, the more slaves 2 connected between each of the multiple slaves 2 and the communication device 1, the larger the delay amount that occurs, and therefore the larger the adjustment value. The overall delay amount of the communication system 100 according to this embodiment is T3 = (6 x T1 + 5 x T2), as shown in Fig. 4. That is, the more slaves 2 daisy-chain connected to the communication device 1, the larger the delay amount of the entire communication system 100.

[0062] The processing unit 111 includes the adjustment values ​​of each slave 2 calculated in the calculation process in a frame F1 and transmits the frame F1 to the first slave 21. The first slave 21 acquires a corresponding adjustment value from among the multiple adjustment values ​​included in the frame F1 and generates a synchronization pulse at a timing based on this adjustment value. The second slave 22 acquires a corresponding adjustment value from among the multiple adjustment values ​​included in the frame F1 received from the first slave 21 and generates a synchronization pulse at a timing based on this adjustment value. The third slave 23 acquires a corresponding adjustment value from among the multiple adjustment values ​​included in the frame F1 received from the second slave 22 and generates a synchronization pulse at a timing based on this adjustment value. The fourth slave 24 acquires a corresponding adjustment value from among the multiple adjustment values ​​included in the frame F1 received from the third slave 23 and generates a synchronization pulse at a timing based on this adjustment value. The fifth slave 25 acquires a corresponding adjustment value from among the multiple adjustment values ​​included in the frame F1 received from the fourth slave 24 and generates a synchronization pulse at a timing based on this adjustment value. Then, each of the first slave 21, the second slave 22, the third slave 23, the fourth slave 24, and the fifth slave 25 performs a predetermined operation (control or detection) in accordance with the generated synchronization pulse. As a result, in the communication system 100 according to this embodiment, it is possible to synchronize the communication device 1 and the multiple slaves 2.

[0063] The plurality of adjustment values ​​for the plurality of slaves 2 calculated in the calculation process are transmitted to each of the plurality of slaves 2 by a SYNC adjustment frame, which will be described later, transmitted from the communication device 1.

[0064] (5) Operation Next, the operations of the communication device 1 and each slave 2 that constitute the communication system 100 according to this embodiment will be described with reference to FIGS.

[0065] (5.1) Communications equipment First, the operation of the communication device 1 will be described with reference to Fig. 5. Fig. 5 is a flowchart showing the operation of the communication device 1 in the communication system 100 of this embodiment.

[0066] The calculation unit 112 of the communication device 1 calculates the maximum number of transmitters for each frame F1 (step S11). In this embodiment, as described above, the maximum number of transmitters is four. That is, in this embodiment, data corresponding to a maximum of four slaves 2 can be included in each frame F1.

[0067] Next, the communication unit 12 of the communication device 1 transmits an initial frame to the first slave 21 (step S12). The initial frame is a frame transmitted for initial setting of each slave 2. The initial frame includes information on the update period CT1 corresponding to each slave 2. The update period CT1 is set by the processing unit 111, as described above.

[0068] Furthermore, the control unit 11 of the communication device 1 determines whether the communication unit 12 has received reply information from the fifth slave 25 in response to the initial frame (step S13). If the control unit 11 determines that the communication unit 12 has received the reply information (step S13: Yes), the communication unit 12 transmits a SYNC adjustment frame to the first slave 21 (step S14). The SYNC adjustment frame includes an adjustment value (SYNC value) for synchronizing the communication device 1 and the multiple slaves 2. Note that steps S12 and S13 are repeatedly executed until reply information is received from the fifth slave 25 (step S13: No).

[0069] Next, the control unit 11 of the communication device 1 determines whether the communication unit 12 has received reply information from the fifth slave 25 in response to the SYNC training frame (step S15). If the control unit 11 determines that the communication unit 12 has received the reply information (step S15: Yes), the communication unit 12 transmits a corresponding frame F1 in accordance with the update period CT1 set for each slave 2 (step S16). Note that steps S14 and S15 are repeatedly executed until reply information is received from the fifth slave 25 (step S15: No). Note that in step S16 of FIG. 5, frame F1 is referred to as a "normal frame."

[0070] (5.2) Slave Next, the operation of each slave 2 will be described with reference to Fig. 6. Fig. 6 is a flowchart showing the operation of each slave 2 in the communication system 100 of the present disclosure. The following description will be given taking as an example the first slave 21, which is the first slave directly connected to the communication device 1 among the multiple slaves 2.

[0071] The communication unit 202 of the first slave 21 receives the initial frame transmitted from the communication device 1 (step S21). The processing unit 201 of the first slave 21 acquires the corresponding update period CT11 from among the multiple update periods CT1 included in the initial frame received by the communication unit 202, and sets the acquired update period CT11 as its own update period CT11 (step S22).

[0072] Next, the communication unit 202 receives the SYNC calibration frame transmitted from the communication device 1 (step S23). The processing unit 201 acquires a corresponding adjustment value from among a plurality of adjustment values ​​(SYNC values) included in the SYNC calibration frame received by the communication unit 202, and synchronizes with the communication device 1 and the other slaves 2 (the second slave 22 to the fifth slave 25) based on the acquired adjustment value.

[0073] Thereafter, the communication unit 202 receives the frame F1 transmitted from the communication device 1 at every reference period CT0, and transmits the frame F1 to the second slave 22 directly connected to the first slave 21 (step S24). Note that in step S24 of FIG. 6, the frame F1 is referred to as a "normal frame."

[0074] (6) Effects As described above, in the communication device 1 according to this embodiment, the update period CT1 (here, update periods CT11 and CT12) of the specific slave 2 (here, the first slave 21 and the second slave 22) having the shortest update period CT1 is set as the reference period CT0. Furthermore, in the communication device 1, the update periods CT1 (here, update periods CT13, CT14, and CT15) of the other slaves 2 (here, the third slave 23, the fourth slave 24, and the fifth slave 25) different from the specific slave 2 are set to integer multiples of the reference period CT0. This prevents the other slaves 2 from being over-specified, and improves communication efficiency. Furthermore, in the communication device 1 according to this embodiment, it is possible to set different update periods CT1 for the specific slave 2 that requires relatively high-speed control and the other slaves 2 that do not require relatively high-speed control, thereby improving the efficiency of the calculation process of the communication device 1.

[0075] Furthermore, in the communication device 1 according to this embodiment, as described above, if the number of slaves 2 corresponding to the data included in the frame F1 is less than the maximum number of transmission devices, the processing unit 111 adds unused data to the frame F1. This makes it possible to make the frame lengths of the frames F1 equal, and as a result, it becomes possible to synchronize the communication device 1 with the multiple slaves 2.

[0076] Furthermore, in the communication device 1 according to this embodiment, as described above, the update period CT14 of the fourth slave 24 and the update period CT15 of the fifth slave 25 are the same. In the communication device 1, the processing unit 111 differentiates the start timing of the update period CT14 from the start timing of the update period CT15 by the reference period CT0. This makes it possible to shorten the frame length of each frame F1 compared to when the start timing of the update period CT14 and the start timing of the update period CT15 are the same.

[0077] (7) Variations The above-described embodiment is merely one of various embodiments of the present disclosure. The above-described embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Furthermore, functions similar to those of the communication device 1 may be embodied in a communication control method, a program (computer program), a non-transitory recording medium on which a program is recorded, or the like.

[0078] A communication control method according to one embodiment is a communication control method used in a communication device 1. The communication device 1 has a plurality of slaves 2 daisy-chained together and communicates with the plurality of slaves 2. The communication control method includes a setting step. In the setting step, the update period CT1 of a specific slave 2, which is the slave with the shortest data update period CT1 among the plurality of slaves 2, is set to a reference period CT0, and the update periods CT1 of other slaves 2 different from the specific slave 2 among the plurality of slaves 2 are set to integer multiples of the reference period CT0. Furthermore, a program according to one embodiment is a program for causing one or more processors to execute the above-described communication control method.

[0079] Modifications of the above-described embodiment are listed below. The modifications described below can be applied in appropriate combinations.

[0080] (7.1) Variation 1 A communication system according to Modification 1 will be described with reference to Fig. 7. Fig. 7 is an explanatory diagram of the update period CT1 of each slave 2 in a communication system according to Modification 1 of the present embodiment. The communication system according to Modification 1 differs from communication system 100 according to the above-described embodiment in that the update period CT1 of each slave 2 is set to twice the update period CT of each slave 2 in communication system 100 according to the above-described embodiment. The communication system according to Modification 1 is otherwise similar in configuration to communication system 100 according to the above-described embodiment, and the same components are denoted by the same reference numerals and description thereof will be omitted.

[0081] In the communication system according to the first modification, as described above, the update period CT1 of each slave 2 is set to twice the update period CT1 of each slave 2 in the communication system 100 according to the above embodiment.

[0082] Specifically, the update period CT11 of the first slave 21 is set to twice the reference period CT0. That is, the update period CT11 of the first slave 21 in the communication system according to Modification 1 is set to twice the update period CT11 of the first slave 21 in the communication system 100 according to the above-described embodiment. Also, the update period CT12 of the second slave 22 is set to twice the reference period CT0. That is, the update period CT12 of the second slave 22 in the communication system according to Modification 1 is set to twice the update period CT12 of the second slave 22 in the communication system 100 according to the above-described embodiment.

[0083] Moreover, the update period CT13 of the third slave 23 is set to four times the reference period CT0. That is, the update period CT13 of the third slave 23 in the communication system according to the first modification is set to twice the update period CT13 of the third slave 23 in the communication system 100 according to the above-described embodiment. Also, the update period CT14 of the fourth slave 24 is set to six times the reference period CT0. That is, the update period CT14 of the fourth slave 24 in the communication system according to the first modification is set to twice the update period CT14 of the fourth slave 24 in the communication system 100 according to the above-described embodiment. Also, the update period CT15 of the fifth slave 25 is set to six times the reference period CT0. That is, the update period CT15 of the fifth slave 25 in the communication system according to the first modification is set to twice the update period CT15 of the fifth slave 25 in the communication system 100 according to the above-described embodiment.

[0084] In the communication system according to the first modification, it is also possible to improve communication efficiency and also to improve the efficiency of the calculation process of the communication device 1.

[0085] In the communication system according to the first modification, the update period CT1 of each of the plurality of slaves 2 is set to a period that is twice the update period CT1 of each of the plurality of slaves 2 in the communication system 100 according to the above-described embodiment, but it is not limited to twice, and may be three or more times.

[0086] (7.2) Other Modifications Other variations are listed below.

[0087] The communication device 1 and slave 2 in the present disclosure include a computer system. The computer system is primarily composed of a processor and memory as hardware. The functions of the communication device 1 and slave 2 in the present disclosure are realized by the processor executing a program stored in the memory of the computer system. The program may be pre-stored in the memory of the computer system, provided via a telecommunications line, or provided in a non-transitory recording medium readable by the computer system, such as a memory card, optical disk, or hard disk drive. The processor of the computer system is composed of one or more electronic circuits, including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). The integrated circuits, such as ICs and LSIs, are referred to by different names depending on the degree of integration, and include integrated circuits called system LSIs, very large scale integrations (VLSIs), or ultra large scale integrations (ULSIs). Furthermore, field-programmable gate arrays (FPGAs), which are programmed after the LSI is manufactured, or logic devices that allow the reconfiguration of internal connections or circuit partitions within the LSI, can also be used as processors. The electronic circuits may be integrated into one chip or distributed across multiple chips. The chips may be integrated into one device or distributed across multiple devices. The computer system referred to here includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller is also composed of one or more electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

[0088] Furthermore, it is not essential for the communication device 1 that multiple functions of the communication device 1 are concentrated in one housing. The components of the communication device 1 may be distributed across multiple housings. Furthermore, at least some of the functions of the communication device 1 may be realized, for example, by the cloud (cloud computing) or the like. Conversely, as in the above-described embodiment, all of the functions of the communication device 1 may be concentrated in one housing.

[0089] Furthermore, it is not essential for the slave 2 that multiple functions are integrated into one housing. The components of the slave 2 may be distributed across multiple housings. Furthermore, at least some of the functions of the slave 2 may be realized, for example, by the cloud (cloud computing). Conversely, as in the above-described embodiment, all of the functions of the slave 2 may be integrated into one housing.

[0090] In the above-described embodiment, the processing unit 111 adds unused data to the frame F1 when the number of slaves 2 corresponding to the data included in the frame F1 is less than the maximum number of transmissions. On the other hand, the processing unit 111 may add an area for storing inter-device data to the frame F1 when the number of slaves 2 corresponding to the data included in the frame F1 is less than the maximum number of transmissions. That is, the inter-device data may be stored in slot D0 of the frame F1. The inter-device data is data transmitted and received between any two of the multiple slaves 2. That is, one of the multiple slaves 2 (e.g., the second slave 22) stores the inter-device data to be transmitted to any of the remaining slaves 2 (e.g., the fourth slave 24) in the area added to the frame F1, and transmits the frame F1 to the next slave 2. This makes it possible to make the frame lengths of the frames F1 equal, thereby enabling synchronization between the communication device 1 and the multiple slaves 2. In other words, the processing unit 111 synchronizes the communication device 1 and the multiple slaves 2 by adding an area for storing inter-device data to the frame F1.

[0091] In the above embodiment, for the fourth slave 24 and the fifth slave 25 that have the same update period CT1, the start timing of the update period CT14 of the fourth slave 24 and the start timing of the update period CT15 of the fifth slave 25 are made to differ by the reference period CT0. In contrast, the start timing of the update period CT14 of the fourth slave 24 and the start timing of the update period CT15 of the fifth slave 25 may differ by more than twice the reference period CT0.

[0092] Furthermore, in the above embodiment, the start timing of the update period CT1 is made different for two slaves 2 (the fourth slave 24 and the fifth slave 25) that have the same update period CT1, but, for example, the start timing of the update period CT1 may be made different for three or more slaves 2 that have the same update period CT1. In short, when the update periods CT1 of two or more slaves 2 out of multiple slaves 2 are the same, the processing unit 111 may make the start timings of the update periods CT1 of the two or more slaves 2 different by at least the reference period CT0.

[0093] Furthermore, the start timing of the update period CT14 of the fourth slave 24 may be the same as the start timing of the update period CT15 of the fifth slave 25. In this case, the maximum number of transmitters in each reference period CT0 is five.

[0094] In the above-described embodiment, the adjustment value calculated by the processing unit 111 is the sum of the first time and the second time, but the adjustment value may also include, for example, a delay time different from the first time and the second time. In short, the adjustment value may be a value based on the first time, which is the processing time from when each of the multiple slaves 2 receives the frame F1 to when it generates a predetermined pulse, and the second time, which is the product of the difference between the number of the multiple slaves 2 and the order of connection from the communication device 1 to each of the multiple slaves 2, and the fixed delay value.

[0095] (Aspect) The present specification discloses the following aspects.

[0096] A communication device (1) according to a first aspect is a communication device that communicates with a plurality of slaves (2) daisy-chained together. The communication device (1) includes a processing unit (111). The processing unit (111) executes a setting process. In the setting process, the update period (CT1) of a specific slave (2) that is the slave with the shortest data update period (CT1) among the plurality of slaves (2) is set to a reference period (CT0), and the update periods (CT1) of other slaves (2) different from the specific slave (2) among the plurality of slaves (2) are set to integer multiples of the reference period (CT0).

[0097] According to this aspect, it is possible to improve communication efficiency.

[0098] The communication device (1) according to the second aspect is the same as that according to the first aspect, and further includes a calculation unit (112). The calculation unit (112) calculates a maximum number of transmission devices. The maximum number of transmission devices is the maximum number of slaves (2) among the multiple slaves (2) that can transmit data in a frame (F1) transmitted from the communication device (1) for each reference period (CT0). The processing unit (111) adds an area to the frame (F1) when the number of slaves (2) among the multiple slaves (2) that corresponds to the data included in the frame (F1) is less than the maximum number of transmission devices calculated by the calculation unit (112). The area is an area for storing inter-device data, which is data between any two slaves (2) among the multiple slaves (2).

[0099] According to this embodiment, it is possible to make the frame lengths of the frames (F1) equal.

[0100] In the communication device (1) according to the third aspect, in the second aspect, the processing unit (111) synchronizes the communication device (1) with a plurality of slaves (2) by adding the above-mentioned region to the frame (F1).

[0101] According to this embodiment, it is possible to synchronize the communication device (1) with a plurality of slaves (2).

[0102] The communication device (1) according to a fourth aspect is the same as that of the first aspect, and further includes a calculation unit (112). The calculation unit (112) calculates a maximum number of transmission units. The maximum number of transmission units is the maximum number of slaves (2) that can transmit data in a frame (F1) transmitted from the communication device (1) for each reference period (CT0). The processing unit (111) adds unused data to the frame (F1) when the number of slaves (2) that correspond to the data included in the frame (F1) is less than the maximum number of transmission units calculated by the calculation unit (112). The unused data is data that is not used in communication between the communication device (1) and the multiple slaves (2).

[0103] According to this embodiment, it is possible to make the frame lengths of the frames (F1) equal.

[0104] In the communication device (1) according to the fifth aspect, in the fourth aspect, the processing unit (111) synchronizes the communication device (1) with a plurality of slaves (2) by adding unused data to the frame (F1).

[0105] According to this embodiment, it is possible to synchronize the communication device (1) with a plurality of slaves (2).

[0106] In the communication device (1) according to a sixth aspect, in any one of the second to fifth aspects, the processing unit (111) further executes a calculation process. In the calculation process, an adjustment value for synchronizing the communication device (1) with the plurality of slaves (2) is calculated. The adjustment value is a value based on a first time and a second time. The first time is a processing time from when each of the plurality of slaves (2) receives the frame (F1) to when it generates a predetermined pulse. The second time is a product of a difference between the number of the plurality of slaves (2) and the connection order from the communication device (1) of each of the plurality of slaves (2), and a fixed delay value.

[0107] According to this embodiment, it is possible to synchronize the communication device (1) with a plurality of slaves (2).

[0108] In a communication device (1) according to a seventh aspect, in any one of the first to sixth aspects, when the update periods (CT1) of two or more slaves (2) among the plurality of slaves (2) are the same, the processing unit (111) makes the start timings of the update periods (CT1) of the two or more slaves (2) different by at least the reference period (CT0).

[0109] According to this aspect, it is possible to shorten the frame length of each frame (F1).

[0110] A communication system (100) according to an eighth aspect includes a communication device (1) according to any one of the first to seventh aspects and a plurality of slaves (2). The plurality of slaves (2) are connected to the communication device (1) and communicate with the communication device (1).

[0111] According to this aspect, it is possible to improve communication efficiency.

[0112] A communication control method according to a ninth aspect is a communication control method used in a communication device (1). The communication device (1) communicates with a plurality of slaves (2) daisy-chained to the plurality of slaves (2). The communication control method includes a setting step. In the setting step, the update period (CT1) of a specific slave (2) that is the slave with the shortest data update period (CT1) among the plurality of slaves (2) is set to a reference period (CT0), and the update periods (CT1) of other slaves (2) different from the specific slave (2) among the plurality of slaves (2) are set to integer multiples of the reference period (CT0).

[0113] According to this aspect, it is possible to improve communication efficiency.

[0114] A program according to a tenth aspect is a program for causing one or more processors to execute the communication control method according to the ninth aspect.

[0115] According to this aspect, it is possible to improve communication efficiency.

[0116] The configurations according to the second to seventh aspects are not essential for the communication device (1) and can be omitted as appropriate. [Industrial Applicability]

[0117] The communication device, communication system, communication control method, and program disclosed herein can provide a communication device with improved communication efficiency, and are therefore industrially useful. [Explanation of symbols]

[0118] 1. Communications equipment 2 Slaves 21 First Slave 22 Second Slave 23 Third Slave 24 Fourth Slave 25 Fifth Slave 100 Communication Systems 111, 201 Processing section 112 Calculation Unit CT0 reference period CT, CT1, CT11, CT12, CT13, CT14, CT15 update cycle F1 Frame P Sync Pulse

Claims

1. A communication device in which a plurality of slaves are daisy-chained and which communicates with the plurality of slaves, a processing unit that executes a setting process of setting the update period of a specific slave, which is a slave with the shortest data update period among the plurality of slaves, to a reference period, and setting the update periods of other slaves, which are different from the specific slave, among the plurality of slaves, to an integer multiple of the reference period; a calculation unit that calculates a maximum number of slaves that can transmit data in frames transmitted from the communication device for each reference period among the plurality of slaves, The processing unit adding an area to the frame for storing inter-device data, which is data between any two of the plurality of slaves, when the number of slaves among the plurality of slaves corresponding to the data included in the frame is smaller than the maximum number of transmission devices calculated by the calculation unit; and executing a calculation process to calculate an adjustment value for synchronizing the communication device with the plurality of slaves; the adjustment value is a value based on a first time and a second time, the first time period is a processing time from when each of the plurality of slaves receives the frame to when it generates a predetermined pulse, the second time is a product of a difference between the number of the plurality of slaves and the order of connection from the communication device to each of the plurality of slaves and a fixed delay value; Communication equipment.

2. The processing unit synchronizes the communication device with the plurality of slaves by adding the region to the frame. The communication device according to claim 1 .

3. A plurality of slaves are daisy-chained, and a communication device for communicating with the plurality of slaves A communication device, a processing unit that executes a setting process of setting the update period of a specific slave, which is a slave with the shortest data update period among the plurality of slaves, to a reference period, and setting the update periods of other slaves, which are different from the specific slave, among the plurality of slaves, to an integer multiple of the reference period; a calculation unit that calculates a maximum number of slaves that can transmit data in frames transmitted from the communication device for each reference period among the plurality of slaves, The processing unit If the number of slaves corresponding to the data included in the frame among the plurality of slaves is less than the maximum number of transmission devices calculated by the calculation unit, unused data that is data that is not used in communication between the communication device and the plurality of slaves is added to the frame, and executing a calculation process to calculate an adjustment value for synchronizing the communication device with the plurality of slaves; the adjustment value is a value based on a first time and a second time, the first time period is a processing time from when each of the plurality of slaves receives the frame to when it generates a predetermined pulse, the second time is a product of a difference between the number of the plurality of slaves and the order of connection from the communication device to each of the plurality of slaves and a fixed delay value; Communication equipment.

4. The processing unit synchronizes the communication device and the plurality of slaves by adding the unused data to the frame. The communication device according to claim 3 .

5. When the update periods of two or more slaves among the plurality of slaves are the same, the processing unit differentiates the start timings of the update periods of the two or more slaves by at least the reference period. The communication device according to any one of claims 1 to 4.

6. A communication device according to any one of claims 1 to 5; the plurality of slaves connected to the communication device to communicate with the communication device; Communication system.

7. A communication control method used in a communication device that communicates with a plurality of slaves connected in a daisy chain, comprising: a setting step of setting the update period of a specific slave, which is a slave with the shortest data update period among the plurality of slaves, to a reference period, and setting the update periods of other slaves, which are different from the specific slave, among the plurality of slaves, to an integer multiple of the reference period; calculating a maximum number of transmission devices, which is a maximum number of slaves that can transmit data in frames transmitted from the communication device for each reference period, among the plurality of slaves; adding an area to the frame for storing inter-device data, which is data between any two of the plurality of slaves, when the number of slaves corresponding to the data included in the frame among the plurality of slaves is smaller than the maximum number of transmission devices; calculating an adjustment value for synchronizing the communication device with the plurality of slaves; the adjustment value is a value based on a first time and a second time; the first time period is a processing time from when each of the plurality of slaves receives the frame to when it generates a predetermined pulse, the second time is a product of a difference between the number of the plurality of slaves and the order of connection from the communication device to each of the plurality of slaves and a fixed delay value; Communication control method.

8. A communication control method used in a communication device that communicates with a plurality of slaves connected in a daisy chain, comprising: a setting step of setting the update period of a specific slave, which is a slave with the shortest data update period among the plurality of slaves, to a reference period, and setting the update periods of other slaves, which are different from the specific slave, among the plurality of slaves, to an integer multiple of the reference period; calculating a maximum number of transmission devices, which is a maximum number of slaves that can transmit data in frames transmitted from the communication device for each reference period, among the plurality of slaves; adding unused data to the frame, the unused data being data that is not used in communication between the communication device and the plurality of slaves, when the number of slaves corresponding to the data included in the frame among the plurality of slaves is smaller than the maximum number of transmission devices; calculating an adjustment value for synchronizing the communication device with the plurality of slaves; the adjustment value is a value based on a first time and a second time; the first time period is a processing time from when each of the plurality of slaves receives the frame to when it generates a predetermined pulse, the second time is a product of a difference between the number of the plurality of slaves and the order of connection from the communication device to each of the plurality of slaves and a fixed delay value; Communication control method.

9. A program for causing one or more processors to execute any one of the communication control methods described in claim 7 or 8.

Images