JPH11167406A - Distributed control system and control method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distributed control system for simultaneously operating more than two controllers without collecting information on the respective controllers by means of a host controller. SOLUTION: The system connects the host controller l and the plural controllers 6A and 6B by a serial communication cable 16. At that time, the serial communication cable 16 is provided with the bi-directional synchronous lines transmitting/receiving synchronizing signals for cooperatively operating the respective controllers 6A and 6B. Time loss at the time of the data communication of the plural controllers 6A and 6B can be eliminated with such constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a distributed control system in which a host control device and a plurality of control devices are connected by serial communication, and a control method of the distributed control system.

[0002]

2. Description of the Related Art Conventionally, a communication system of a programmable controller for performing data communication between a master controller and a slave controller is disclosed in Japanese Patent Application Laid-Open No. 3-204006.
No. 6,086,045.

In this communication system, among a plurality of programmable controllers each having a unique address, a programmable controller having an interface unit connectable to a host controller is used as a master controller, and the other programmable controllers are used as slave controllers. The link units for data communication provided respectively are connected via a transmission line.

[0004] The host controller instructs the master controller of the address of the slave controller with which data communication is to be performed, and transmits data to a plurality of slave controllers via the master controller. By repeating this, one-to-many data communication can be executed.

[0005] The host controller can perform data communication with all the programmable controllers in the communication system via the master controller. Therefore, the host controller can change or collect data of each programmable controller. Of course, it is also possible to monitor the overall operation of the communication system.

[0006]

However, in the above-mentioned prior art, there is a problem that all data communication must be performed via a master controller.

That is, in order to operate another slave controller or to execute a command such that a plurality of slave controllers operate synchronously in accordance with the state of a certain slave controller, information of the slave controller is transmitted to the master controller. Must be collected by the host controller via the controller, and new data must be transmitted to other slave controllers via the master controller.

[0008] In such a communication system that performs data communication via the master controller, there is a problem that a time loss occurs during the data communication and that a plurality of slave controllers cannot operate in conjunction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and makes it possible to simultaneously operate two or more sub-controllers without collecting information of each sub-controller by a host controller. It is an object of the present invention to provide a distributed control system and a control method of the distributed control system that can eliminate a time loss during data communication.

[0010]

According to the first aspect of the present invention,
In a distributed control system in which a main control device and a plurality of sub-control devices are connected by a serial communication cable, the cable includes a signal line for transmitting and receiving a synchronization signal for operating the sub-control devices in cooperation with each other. It is characterized by the following.

According to the present invention, since the serial communication cable is provided with a signal line for transmitting and receiving a synchronization signal for operating the respective sub-controllers in cooperation, the sub-controllers are connected using the serial communication cable. This makes it possible to reduce the number of data transmissions from the main control device and to eliminate time loss in data communication.

According to a second aspect of the present invention, the main control device and the plurality of sub-control devices are linked to each other, and a data line for transmitting and receiving a control signal between the main control device and each sub-control device is linked to each sub-control device. A method of controlling a distributed control system that performs serial communication by coupling with a cable having a signal line that transmits and receives a synchronization signal for operating the sub-controller, wherein the main controller operates the sub-controllers in cooperation with each other. , Based on the signal state of the synchronization signal.

According to the present invention, when the main control device operates the respective sub-control devices in cooperation with each other, the main control device performs the operation on the synchronization line of the cable based on the signal state of the transmitted synchronization signal. Control for operating the sub-controllers in synchronization with each other without the intervention of the host controller can be realized.

According to a third aspect of the present invention, in the second aspect of the present invention, the synchronization signal is created by any of the sub-control devices that operate in cooperation.

According to the present invention, it is possible to generate the synchronization signal without intervening the host control device and to operate the plurality of sub-control devices in synchronization.

[0016]

Embodiments of the present invention will be described below in detail.

FIG. 1 is a block diagram showing an example of the configuration of the distributed control system according to the present embodiment, and FIG. 2 is a diagram showing the cable configuration of the serial communication cable 16 shown in FIG.

This distributed control system comprises a master controller 2 which can be connected to the host controller 1, a plurality of controllers 6A, 6B,...
And a serial communication cable 16 for coupling the plurality of control devices 6A, 6B,..., 6N.

The master controller 2 is a communication controller 3 for performing data communication with a plurality of control devices 6A, 6B,..., 6N via a serial communication cable 16.
A programmable memory 4 connectable to the host control device 1; and an arithmetic control unit 5 connected to both the communication controller 3 and the programmable memory 4 and connected to the host control device 1.

The control device 6A includes a communication controller 3a,
A device control unit 7a, an address setting unit 8a for determining a unique address, a communication interface unit 9a connected to the serial communication cable 16, a synchronization line 10a provided between the device control unit 7a and the communication interface unit 9a, an external interface Unit 14a, the device control unit 7a
Is an external device 15 through the external interface unit 14a.
A is controlled.

The control device 6B, like the control device 6A,
A communication controller 3b, a device control unit 7b, an address setting unit 8b for determining a unique address, a communication interface unit 9b connected to the serial communication cable 16, and a synchronization line provided between the device control unit 7b and the communication interface unit 9b. 10b, an external interface unit 14b is provided, and the device control unit 7b controls the external device 15B via the external interface unit 14b.

The control device 6N, like the control device 6A,
A communication controller 3n, a device control unit 7n, an address setting unit 8n for determining a unique address, a communication interface unit 9n connected to the serial communication cable 16, and a synchronization line provided between the device control unit 7n and the communication interface unit 9n. 10n and an external interface unit 14n. The device control unit 7n includes the external interface unit 1
The control of the external device 15N is performed via 4n. The following description will be made assuming that N and n are positive integers.

As shown in FIG. 2, the serial communication cable 16 is connected to the master controller 2 and the communication interfaces 9 of the control devices 6A, 6B,.
, 9n, two bidirectional data lines 17 and two bidirectional synchronization lines 18 are connected.

Each of the device control sections 7a, 7b,..., 7n has a program for outputting a synchronization signal when receiving a command from the host control device 1, and a command for receiving a command from the host control device 1 when the synchronization signal is input. And a program for executing the program.

[Operation] Next, the operation of the first embodiment having the above configuration will be described. Plurality of control devices 6A, 6
, 6N are assigned unique addresses by the address setting units 8a to 8n. Here, it is assumed that the control devices operated in conjunction with each other are the control devices 6A and 6A.
The following description is made on the assumption that B is two.

The host controller 1 selects, via the master controller 2, either the controller 6A or the controller 6B as a reference device. The reference device indicates which control device is used as a reference for operation. Now, suppose that the control device 6A
Is selected as the reference device, and a drive command for the two external devices 15A and 15B connected to the control devices 6A and 6B is transmitted from the host control device 1.

In the control device 6A to which the drive command has been sent from the host control device 1 via the master controller 2, a synchronization signal is transmitted from the device control portion 7a to the communication interface portion 9a via the synchronization line 10a. The synchronization signal input to the communication interface unit 9a is input again to the device control unit 7a, and the serial communication cable 16
Is transmitted to the communication interface unit 9b of the control device 6B via the bidirectional synchronization line 18 in the inside.

Similarly, the synchronization signal input to the communication interface 9b is transmitted to the device controller 7 via the synchronization line 10b.
b.

Each of the control devices 6A and 6B sends a drive command from the host control device 1 to the external interface unit 14 at the same time when a synchronization signal is input to the device control units 7a and 7b.
a and 14b to the external devices 15A and 15B, respectively. Thereby, these external devices 15A and 15B are driven synchronously.

In this manner, the two control devices 6A and 6B can be operated in cooperation without the intervention of the host control device 1, and the time loss in data communication can be reduced as compared with the case where the host control device 1 is used. Can be.

Note that, even if the reference device is replaced or three or more control devices are connected, the operation is the same as that described above.

(Embodiment 2) Embodiment 2 of the present invention will be described with reference to FIGS. 3, 4, 5, and 6. FIG.

[Configuration] FIG. 3 is a block diagram showing the configuration of the distributed control system according to the second embodiment of the present invention, FIG. 4 is a diagram showing the cable configuration of a communication cable 34, and FIG.
8 is a flowchart of a program processed by FIG. 8, and FIG. 6 is a flowchart of a program processed by the CPU 24a of the actuator control device 23A.

This distributed control system comprises a master controller 19 which can be connected to a host controller 38, and actuator controllers 23A and 23B which are a plurality of controllers.
, 23N, and a serial communication cable 34 connecting the master controller 19 and the plurality of actuator controllers 23A, 23B, ..., 23N.

The master controller 19 which can be connected to the host controller 38 includes a communication controller 20 for performing data communication, a programmable memory 21 which can be connected to the host controller 1, and both the communication controller 20 and the programmable memory 21. Operation control unit 2 connected
2 is provided.

The master controller 19 and the plurality of actuator controllers 23A, 23B,.
As shown in FIG. 4, they are interconnected by a serial communication cable 34 including two bidirectional data lines 35 and two bidirectional synchronization lines 36.

The actuator control device 23A includes a communication controller 20a and a CPU 24 serving as a device control unit.
a, an address setting unit 25a for determining a unique address,
A communication interface unit 30a such as RS-485 connected to the serial communication cable 34, a unidirectional synchronization signal line provided between the communication interface unit 30a and the CPU 24a and transmitting a synchronization signal to another actuator control device 23B or the like. 28a, a unidirectional synchronization receiving line 29a for receiving a synchronization signal, and an external interface unit 26a.
The motor driver 31A is connected to the external motor 32A and the detector 33A through 6a, and controls the motor driver 31A.

The actuator control device 23B is, like the actuator control device 23A, a communication controller 20b, a CPU 24b serving as a device control unit, an address setting unit 25b for determining a unique address, and an RS-connector connected to a serial communication cable 34. 485 and the like, and the communication interface 30b and C
A unidirectional synchronization signal line 28b for transmitting a synchronization signal to another actuator control device 23A or the like, and a unidirectional synchronization reception line 29 for receiving a synchronization signal.
b, an external interface unit 26b,
U24b is connected to a motor driver 31B to which an external motor 32B and a detector 33B are connected through an external interface unit 26b.
Is controlled.

Similarly to the actuator control device 23A, the actuator control device 23N has a communication controller 20n, a CPU 24n as a device control unit, an address setting device 25n for determining a unique address, and an RS-connector connected to a serial communication cable 34. 485 or the like, a communication interface 30n, a communication interface 30n and C
A one-way synchronization signal line 28n for transmitting a synchronization signal to another actuator control device 23A and the like, and a one-way synchronization reception line 29 for receiving a synchronization signal.
n, an external interface unit 26n,
U24n is connected to a motor driver 31N to which an external motor 32N and a detector 33N are connected through an external interface unit 26n, and controls the motor driver 31N.

Each of the actuator control devices 23A, 2
Each of the CPUs 24a and 24b in the 3B outputs a synchronizing signal when receiving a command from the host control device 30 when it is the reference device, and a program that executes the command of the host control device 38 when the synchronizing signal is input. Is incorporated.

[Operation] Next, the operation of the distributed control system according to the second embodiment will be described with reference to FIGS. 5 and 6 as well, and simple linear interpolation of the two motors 32 by the two actuator controllers 23A and 23B. The operation will be described as an example.

Here, the simple linear interpolation operation and the overall control conditions (initial speed, acceleration, maximum speed, moving position, etc.) are set, and two control signals are transmitted according to the synchronization signal transmitted between the actuator control devices 23A and 23B. This refers to an operation of operating the motors 32, 32 simultaneously.

Conventionally, an X-axis control device for controlling an X-axis motor and a Y-axis control device for controlling a Y-axis motor are individually controlled by a host control device to form an XY table. , The X-axis control conditions (initial speed, acceleration, maximum speed, moving amount, etc.) and the Y-axis control conditions are input to the host controller, respectively, and the host controller and the X-axis controller It is necessary to operate while communicating control conditions with the Y-axis control device.

In the distributed control system according to the second embodiment, first, a plurality of actuator control devices 23A, 23
, 23N, address setting units 25a,
, 25n, a unique address is set.

The host controller 38 issues a command using the actuator controller 23A as a reference device via the master controller 19 to each of the actuator controllers 23A and 23A.
B,..., 23N and the actuator controller 23
A is selected as the reference device (step S1). Here, the reference device means a device serving as a reference for any one of the two actuator control devices 23A and 23B for which a simple linear interpolation operation is to be executed.

Next, the host controller 38 controls the moving position of the motor 32A controlled by the actuator controller 23A and the motor 3 controlled by the actuator controller 23B.
2B movement position and actuator control devices 23A,
The parameters such as the combined speed of the motors 32A and 32B controlled by the 3B are controlled by the arithmetic and control unit 22 of the master controller 19.
(Step S2).

Further, after transmitting the parameters, the host control device 38 transmits a drive command to the master controller 19 (step S3).

Operation control unit 2 in master controller 19
2 calculates the speeds of the respective directional components of the actuator control devices 23A and 23B based on the parameters from the host control device 38, and uses the two parameters in the communication controller 20 and the serial communication cable 34 for the calculated parameters such as the speed. Actuator controller 23 via bidirectional data line 35
A, 23B.

As shown in FIG. 6, the CPU 2 of the actuator control device 23A which is the reference device (step S11)
4a receives the parameter (step S12),
Upon receiving the driving command, the CPU 24a transmits a synchronization signal to the communication interface 30a via the synchronization signal line 28a based on a preset program (Step S).
13).

The communication interface 30a to which the synchronization signal has been sent returns the synchronization signal to the CPU 24a again via the synchronization reception line 29a. The synchronization signal is sent as differential data to the actuator control device 23B via the bidirectional synchronization line 36 in the serial communication cable 34, and is input to the communication interface 30b. Further, this synchronization signal is sent to the CPU 24b via the synchronization reception line 29b.

As described above, when the synchronization signals are input to both the CPUs 24a and 24b of the actuator control devices 23A and 23B, the CPUs 24a and 24b execute the movement command at the same time and start driving the motors 32A and 32B at the same time (step). S14) The motors 32A and 32B are simultaneously driven at the speed calculated by the arithmetic and control unit 22 in the master controller 19.

The actuator controller 23 which is not a reference device but a device for performing linear interpolation (step S15).
B receives the parameters from the arithmetic control unit 22 (step S16), and then proceeds to the processing of step S14. Further, the processing is terminated for a device that is not a reference device and is not a device that performs linear interpolation (for example, the actuator control device 23N).

[Effects] According to the second embodiment, the synchronization signal and the two actuator control devices 23A and 23B are used.
Is used, a simple linear interpolation operation for operating the two motors 32A and 32B in synchronization with each other can be performed, and a time loss in data communication can be reduced as compared with the case where the host controller 20 is used. The number of times can also be reduced.

(Embodiment 3) Embodiment 3 of the present invention will be described with reference to FIGS. 7, 8, 9 to 11. FIG.

[Configuration] FIG. 7 is a block diagram showing the configuration of the distributed control system according to the third embodiment, FIG. 8 is a detailed diagram of a communication cable, FIG. 9 is a flowchart of a program processed by the host control device 60, and FIG. Is a flowchart of a program processed by the CPUs 43a to 43n of the actuator control devices 42A to 42N, and FIG. 11 is a flowchart of a program processed by the CPUs 54a to 54n of the I / O control devices 53A to 53N.

The distributed control system according to the third embodiment includes a host controller 60, a master controller 61, a plurality of actuator controllers 42A to 42N, a plurality of I / Os.
Control devices 53A to 53N and serial communication cable 5
7 is provided.

The master controller 61, a plurality of actuator controllers 42A to 42N and a plurality of I / Os
The O control devices 53A to 53N are connected by a serial communication cable 57 including two bidirectional data lines 58 and two bidirectional synchronization lines 59 shown in FIG.

The actuator control unit 42A includes a communication controller 39a, a CPU 43a, an address setting unit 44a for determining a unique address, and an RS-485.
, A unidirectional synchronous transmission line 48a for transmitting a synchronous signal to another actuator control device 42N, etc., and another actuator control device 42B.
One-way synchronous receiving line 49a for receiving a synchronous signal from
And an external connection interface unit 62a.

The CPU 43a is connected to a motor driver 50A to which a motor 51A and a detector 52A are connected via an external interface 62a, and controls the motor 51A through the motor driver 50A.

Similarly to the actuator control unit 42A, the actuator control unit 42N includes a communication controller 39n, a CPU 43n, an address setting unit 44n for determining a unique address, and a communication interface unit 45n including an RS-485 and the like. A unidirectional synchronous transmission line 48n for transmitting a synchronous signal to the other actuator control device 42A and the like, a unidirectional synchronous reception line 49n for receiving a synchronous signal from the other actuator control device 42A and the like,
An external connection interface 62n is provided.

The CPU 43n is connected to a motor driver 50N to which the motor 51N and the detector 52N are connected via an external interface 62n, and controls the motor 51N through the motor driver 50N.

The I / O control unit 53A includes a communication controller 79a, a CPU 73a, an address setting unit 74a for determining a unique address, a communication interface 75a such as RS-485, and another I / O control unit 53N.
A unidirectional synchronous transmission line 48a for transmitting a synchronous signal
A unidirectional synchronous receiving line 49a for receiving a synchronous signal from another I / O control device 53N or the like;
2a.

The CPU 73a is connected to the input device 55A and the output device 5 via the external connection interface 72a.
6A is controlled.

The I / O control device 53N includes a communication controller 79n and a CP, similarly to the I / O control device 53A.
U73n, an address setting unit 74n for determining a unique address, and a communication interface 75 such as RS-485.
n, a unidirectional synchronous transmission line 48n for transmitting a synchronous signal to another I / O control device 53A and the like, and another I / O control device 5A.
Unidirectional synchronous receiving line 49 for receiving a synchronous signal from 3A or the like
n and an external interface unit 72n.

The CPU 73n is connected to an input device 55N and an output device 56N via an external interface 72n.
Is controlled.

C in the actuator control device 42A
The PU 43a is provided with a program for executing a command from the host control device 60 when a synchronization signal is input. The CPU 73a of the I / O control device 53A detects a synchronization signal when an input signal from the input device 55 is detected. The program which outputs is installed.

[Operation] Next, the operation of the third embodiment will be described. In the distributed control system according to the second embodiment,
First, a plurality of actuator control devices 42A to 42A
N, for a plurality of I / O control devices 53A to 53N,
A unique address is assigned by each of the address setting units 44a to 44n and the address setting units 74a to 74n.

Now, a plurality of actuator control devices 42A
To 42N and a plurality of I / O control devices 53A to 53N
One by one, ie, the actuator control device 42
A, a case will be described as an example where the I / O control device 53A is used to input an operation signal from the input device 55 connected to the I / O control device 53A and simultaneously drive the motor 51A.

The host control device 60 is provided with the I / O control device 5
A plurality of actuator control devices 42A to 42N and a plurality of I / O control devices 53A are used to issue a command using 3A as a reference device.
To 53N via the master controller 61,
The I / O control device 53A is selected as a reference device (step S21). Here, the reference device refers to a device serving as a reference for operation among the actuator control device 42A and the I / O control device 53A, as in the case of the second embodiment.

Next, the host controller 60 transmits parameters such as the moving position and speed of the motor 51A connected to the actuator controller 42A to the actuator controller 42 via the master controller 61 and the serial communication line 57.
A, transmitting to the I / O control device 53A (step S2
2).

Further, after transmitting the parameters, the host control device 60 issues a drive command via the serial communication line 57 to the actuator control device 42A, the I / O control device 5
3A (step S23).

The actuator control device 42A is not a reference device (step S31) but is a device that operates synchronously (step S35). The actuator control device 42A receives the parameters from the host control device 60 (step S36) and receives a drive command. Then, since the synchronization signal has not been input yet, the apparatus enters a standby state (step S33).

On the other hand, the reference device (step S4)
1) The CPU 74a of the I / O control device 53A transmits an input signal from the input device 55A to the external connection interface unit 7.
2a (step S42), the synchronous transmission line 4
A synchronization signal is transmitted to the communication interface 75a via the communication interface 75a.

The communication interface unit 75a, to which the synchronization signal has been input, returns to the CPU 7 via the synchronization reception line 49a.
3a and the serial communication cable 5
A synchronization signal is transmitted as differential data to the communication interface 45a of the actuator control device 42A via the bidirectional synchronization line 59 in Step 7 (Step S43).

The communication interface unit 45a transmits the transmitted synchronization signal to the CPU 43a via the synchronization signal line 49a.
Send to

Here, the CPU 73a of the I / O control device 53A to which the synchronizing signal has been inputted does not cause any problem because no program to be executed is set.

On the other hand, the CPU 43a of the actuator control device 42A to which the synchronization signal has been input transmits a drive command to the motor driver 50A, and starts driving the motor 51A (step S34).

If the reference device is replaced,
As shown in steps S45 and S46 in FIG.
It is also possible to execute the output command after receiving the synchronization signal in the CPU 73a of the control device 53A.

[Effects] According to the present embodiment, the synchronization signal and the actuator control devices 42A to 42N,
By using the I / O control devices 53A to 53N,
The motors 51A to 51N can be driven at the same time as the input signals are detected by the I / O controllers 53A to 53N without the intervention of the host controller 60.

According to the present invention described above, the following configuration can be added. (1) In a distributed control system including a host control device and a plurality of control devices, wherein the host control device and the plurality of control devices are connected by a serial communication cable, the serial communication cable includes a data line and a data line. A synchronization line is provided, and the host control device sends a command that an arbitrary number of the control devices operate in conjunction with each other, and each of the control devices transmits the command based on a state of a synchronization signal transmitted on the synchronization line. A distributed control system for executing the command from a host control device. According to this configuration, the host control device sends a command through which any number of the control devices operate in conjunction with each other through the serial communication cable, and the control devices transmit the synchronization signals transmitted through the synchronization line of the serial communication cable. Since the command from the host control device is executed based on the state of the signal, each control device can be operated synchronously based on the synchronization signal without passing through the host control device.

(2) In a control method for a distributed control system comprising a host control device and a plurality of control devices and connecting the host control device and the plurality of control devices with a serial communication cable, the host control device may be A command for operating an arbitrary number of the control devices in conjunction with each other is issued, and the arbitrary number of the control devices receiving the command is based on a signal state transmitted by a synchronization line provided in the serial communication cable. A control method for a distributed control system in which an arbitrary number of the control devices are operated in conjunction with each other by executing the command. According to the control method of the distributed control system, it is possible to realize a control for operating the respective controllers in synchronization based on the synchronization signal without passing through the host controller.

[0082]

According to the first aspect of the present invention, since a serial communication cable is provided with a signal line for transmitting and receiving a synchronous signal for operating the respective sub-controllers in cooperation with each other, the serial communication cable is used for sub-control. By connecting the control devices, it is possible to provide a distributed control system capable of reducing the number of data transmissions from the main control device and eliminating a time loss in data communication.

According to the second aspect of the present invention, when the main control device operates the sub-control devices in cooperation with each other, the operation is performed based on the signal state of the synchronization signal transmitted through the synchronization line of the cable. Accordingly, it is possible to provide a control method for a distributed control system capable of realizing control for operating a plurality of sub-controllers in synchronization without intervening a host controller.

According to the third aspect of the present invention, the synchronizing signal is generated by any of the sub-control devices that perform the cooperative operation. Therefore, the synchronizing signal is generated without passing through a host control device. Thus, it is possible to provide a control method for a distributed control system capable of operating a plurality of sub-control devices in synchronization.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a distributed control system according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a cable configuration of a serial communication cable according to the first embodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration of a distributed control system according to a second embodiment of the present invention.

FIG. 4 is a schematic diagram showing a cable configuration of a serial communication cable according to a second embodiment of the present invention.

FIG. 5 is a flowchart of a program processed by a host control device according to Embodiment 2 of the present invention.

FIG. 6 is a flowchart of a program processed by a CPU according to the second embodiment of the present invention.

FIG. 7 is a block diagram illustrating a configuration of a distributed control system according to a third embodiment of the present invention.

FIG. 8 is a schematic diagram illustrating a cable configuration of a serial communication cable according to a second embodiment of the present invention.

FIG. 9 is a flowchart of a software program processed by the host control device according to the third embodiment of the present invention.

FIG. 10 is a flowchart of a program processed by a CPU of an actuator control device according to Embodiment 3 of the present invention.

FIG. 11 is a flowchart of a program processed by a CPU of an I / O control device according to Embodiment 3 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Host controller 2 Master controller 3 Communication controller 4 Programmable memory 5 Arithmetic controller 6A Controller 6B Controller 6C Controller 7a Equipment controller 8a Address setter 9a Communication interface unit 10a Synchronization line 15A External device 16 Serial communication cable 17 Both Data line 18 Bidirectional synchronization line

Claims (3)

[Claims] 1. A distributed control system in which a main control device and a plurality of sub-control devices are connected by a serial communication cable, wherein the cable transmits and receives a synchronization signal for operating the respective sub-control devices in cooperation with each other. A distributed control system, comprising: 2. A data line for transmitting and receiving a control signal between the main control device and each of the sub-control devices, and a synchronization for operating the sub-control devices in cooperation with each other. A method of controlling a distributed control system that performs serial communication by coupling with a cable having a signal line for transmitting and receiving a signal, wherein when the main control device operates the sub-control devices in cooperation with each other, a signal of the synchronization signal is transmitted. A control method for a distributed control system, wherein the method is performed based on a state. 3. The control method for a distributed control system according to claim 2, wherein the synchronization signal is created by any of the sub-control devices that operate in cooperation.