JPH04184501A - Process data processing system - Google Patents

Abstract

PURPOSE:To eliminate the need of an exclusively used computer for inputting and outputting data from and to an object to be controlled so as to reduce the cost of the system by providing a scanning device which is exclusively used for inputting and outputting data from and to a process input-output device. CONSTITUTION:A computer 1 writes control data and transferring periods for dividing the area of a process data memory 10 in a memory controller 20. A communication controller 30 transmits data in accordance with this set information after fetching the data from the memory 10 and writes the data contained in a frame received through a communication channel 70 in the memory 10. A scanning device 40 writes the data for deciding the division and period for transmission and reception of each area of a process data memory 12 in a memory controller 22 in accordance with a command from the computer 1 and a communication controller 32 performs the transmitting and receiving operations on each area on the basis of the data. Therefore, the cost of this process data processing system can be reduced, because no special computer is required between the computer 1 and the process input-output devices for inputting and outputting data.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a process data processing system, and in particular,
The present invention relates to a process data processing system in which a plurality of communication control devices are connected via a transmission path and a cyclic communication method is adopted for data exchange between the communication control devices.

[Prior Art] In the conventional cyclic communication method, a transmission side communication control device transmits information in a memory at fixed time intervals, and each reception side communication control device receives the information after a certain delay time. It had become. The computer connected to each receiving communication control device constantly updates the received data in its memory, so it can use the data freely when it is needed, and the data sent by the transmitting communication control device can be used by other computers. Since data can be received by all receiving side communication control devices, there is no need for the computer connected to the sending side communication control device to send data to each receiving station one by one. This has the advantage that processing can be reduced.

The data subject to cyclic communication is
For example, it is process data for process control, as seen in No. 258534 and Japanese Patent Laid-Open No. 57-206924.

Japanese Patent Laid-Open No. 62-258534 employs a cyclic communication method in which a computer transmits or receives process data at regular intervals. Collection of process data is executed by a computer connected to each communication control device in the network.

On the other hand, Japanese Patent Laid-Open No. 57-206924 adopts a configuration in which a dedicated control device is installed for each process monitoring control target, and these control devices are connected through a communication network to distribute the load. The process control target is connected to a communication network via multiple process input/output devices,
Each control device takes in the necessary process control data from the process input/output devices under it and processes it, but when data from a process input/output device that is not under it is required, it Executes data communication with the controlling control device and obtains the necessary data.

[Problem to be solved by the invention]

In the conventional process control method using cyclic communication,
Computers connected to communication control devices that make up the network input and output data to and from process input/output devices, so if the computer and process input/output device are far apart, data input and output from the process input/output device is possible. This has the disadvantage of requiring a separate computer for output, resulting in high costs.

On the other hand, in conventional distributed processing type process control devices, each control device has a configuration in which only the data about the process input/output devices under its own control is held, so data held by other control devices is needed. In this case, it is necessary to perform data communication with the computer that holds the data at the required timing.

During this data communication process, system responsiveness decreases and
There was a problem that control performance was impaired.

In addition, in conventional process control systems, when a process input/output device is removed or otherwise changed, the control device directly inputs and outputs data. This has caused problems such as non-mounted errors indicating that the device is not mounted, which can be a fatal failure for the control device's computer.

An object of the present invention is to provide an inexpensive process control system that does not require a dedicated computer for data input/output to variously arranged control objects.

Another object of the present invention is to have high responsiveness, flexible operating configurations, and system constructability without causing failures such as non-installation errors on the control device side even when updating process input/output devices, etc. Our goal is to provide process control systems.

[Means to solve the problem]

In order to achieve the above object, the present invention proposes a process control system equipped with a scanning device that is much cheaper than a dedicated computer and that specializes in inputting and outputting data to a process input/output device.

In order to achieve the objective of the above-mentioned function, the present invention enables a scanning device to set implementation information of a process input/output device in response to a command from a computer, store it in a process data memory as a response to the command, and store it in a process data memory as a response to the command. This paper proposes a cyclic communication method that notifies computers of changes in the implementation status of output devices.

More specifically, the scanning device includes an address memory that receives address data from the process data memory according to a command from the computer and stores this data in order;
It is provided with a direction memory that receives data indicating the address and input/output direction of the process input/output device according to a command from the computer and stores the data in order.

The scanning device accesses the address memory and the direction memory simultaneously, and when the input/output direction of the direction memory is the input side,
The data read from the address of the process input/output device indicated in the direction memory is written to the address of the process data memory indicated in the address memory. On the other hand, when the input/output direction of the direction memory is the output side, process data is read from the process data storage address indicated in the address memory and written to the address of the process input/output device indicated in the direction memory.

[Operation] In the present invention, since each computer has all the data of the controlled objects of the process input/output device, it can obtain necessary data by referring to its own memory. Therefore, inter-computer data communication for data acquisition is not required, improving system responsiveness and control performance.

The mounting information of the process input/output device is set in the scanning device by a command from the computer, and when the process input/output device is changed, the mounting information is changed. If you reissue the command, the unimplemented error will not occur. Since the computer takes in the data sent by the scanning device via its own communication control device and process data memory, no non-implementation errors occur on the computer side.

When acquiring data from a process control target, a computer simultaneously and sequentially accesses the address of the data to be acquired on the process input/output control device and the address on the memory where the data is stored, and at a predetermined period through cyclic communication. Send. By making the period sufficiently shorter than the rate of change of the process, the latest data can be obtained with the required accuracy.

The computer is not directly connected to the process control device, but is connected indirectly via the process data memory, which improves system construction and allows the process control device to be separated for maintenance, making it easy to maintain. becomes.

[Example]
・.

Next, an embodiment of the process control system according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a process control system including a command control device according to the present invention.

The process control system includes a plurality of computers 12 that control processes of a process control target 60 in a distributed manner, and a communication control device 3 that is connected, for example, in a circular manner by a communication path 70.
0, 31, 32, 33, a process data memory 10.11 connected between each computer 1.2 and a communication control device 30.31, and a process data memory 10.
11, and memory control devices 20 and 21 that respectively manage input/output and cyclic communication cycles.

The process control system also includes a communication controller 32.3
A process input/output device 50.51 and a process input/output device 50.5 provided between the control target 3 and the controlled object 60, respectively.
a scanning device 40.41 for scanning each of the scanning devices 12.1, and a process data memory 12.41 connected between each scanning device 40, 41 and the communication control device 32.33, respectively; l
, 3, and a memory control device 22.23 that manages the input/output of the process data memory 12.13 and the period of cyclic communication, respectively.

FIG. 2 is a block diagram showing in more detail the connections among the computer 1, the process data memory 1O, and the communication control device 30.

The computer 1 includes a central processing unit (CPU) 80, a data memory 81, a program memory 82, and an address bus 83 and a data bus 84 that connect these. Address bus 83 and data bus 84 are also connected to process data memory 10 and memory controller 20. The process data memory 10 and the memory control device 20 are connected to the communication control device 30 through another set of address buses and data buses, respectively.

The configuration of the computer 2t process data memory 11° communication control device 31 is as follows: computer 1, process data memory 10. This is the same as the communication control device 3o.

The CPU 80 executes necessary calculations using the process data of the controlled object 60 stored in the data memory 81 according to the program stored in the program memory 82 , and processes the process controlled object 6 via the communication control device 30 .
Controls 0 processes. To realize this control, it is necessary to determine the transmission area, reception area and transfer period in the process data memory 10.

The CPU 80 divides the process data memory 10 into areas according to the program in the program memory 82, as shown in FIG. Capital letters such as A and E shown in the process data memory 10 represent transmission areas, and b, c,
Lowercase letters such as d represent reception areas. This uppercase and lowercase notation system is used for other process data memory 1
The same applies to 1, 12, and 13, where uppercase letters represent the transmission area and lowercase letters represent the reception area.

cpuso writes control data for dividing areas and a transfer cycle into the memory control device 20.

The communication control device 30 retrieves data from the process data memory 10 and transmits it according to the setting information written in the memory control device 20. It also captures data in the received frame sent through the communication path 70 and writes this data into the process data memory 1o.

Therefore, the computer 1 has a process data memory 10
Write data to or process data memory 10
By reading data at a predetermined timing from
It is possible to send and receive process data and control the process control target 60.

FIG. 3 is a block diagram showing in more detail the connections among the input/output device 50, the scan device 40, the process data memory 12, the memory control device 22, and the communication control device 32.

The scanning device 40 includes a processing device 42, a program data memory 43. Address memory 44 and direction memory 45 are connected by address bus 83 and data bus 84. Address bus 83 and data bus 84 are connected to external process data memory 12 and memory control device 2.
It is connected to 2. External process data memory 1
2 and the memory control device 22 are connected to a transfer control device 47. The transfer control device 47 is further connected to a counter 46 for knowing the transmission timing. Transfer control device 47 controls reading and writing of data between process data memory 12 and process input/output device 50 .

When the scanning device 40 is powered on,
Separate the sending area and receiving area as indicated by a, b, c, and d in Figure 2. For example, area C is the area for receiving commands from computer 1, and area C is the area for sending responses to the commands. I'll keep it. other ev f
Since the e g+h area is to be divided in the future by a command, it is still in an undivided state when the power is turned on. The classification information of the command response area is set in the memory control device 22 connected to the scanning device 40, so that it can receive commands from the computer 1.

An example of the command format is shown in FIG.

In this embodiment, the command format includes the destination device number Al, command A2. Command identification number A3. It has data A4, \Al for command issuing, and command processing details A2. A3 and data A4 accompanying the command will be transmitted.

On the scanning device 40 side, the command format is referred to and the command is processed according to the procedure shown in FIG. In the flowchart of FIG. 6, the scanning device 40 determines whether the command is addressed to itself, and if the command is addressed to itself, determines whether the command identification number is different from the previous command identification number.

This process prevents processing the same command multiple times. If the command identification number is different from the previous command, the command is processed and the processing result is written in area G in FIG. 4 as a response. The content to be written is that the command processing has completed successfully.

This is information such as whether there was an abnormality or whether there was an abnormality in the command parameters.

The details of control by commands are described below.

First, data is set in the address memory 44 and direction memory 45. Data that associates the X address of the process data memory l2 with the Y address of the process input/output device 5o is set in the address memory 44. Further, direction data indicating whether the access direction is from address X to address Y or from address Y to address X is set in the direction memory 45. Next, separate commands are used to set the e, flg, and h area classification data and transfer period. In response to the command, the scanning device 40 writes data determining the transmission/reception classification and cycle of the e+f+g+h area into the memory control device 22. From this point on, the communication control device 32 uses areas e, f, g, and h based on the written data on the classification and period.
Starts the sending/receiving operation. Finally, scanning device 4
0, issues a command instructing the start of data transfer between the process data memory 12 and the process input/output device 50, and transfers the process of the process control target 60 between the process data memory 12 and the process input/output device 50. Let data be exchanged.

The above processing is performed on each computer 1, 2 and the scanning device 40.41.
When implemented for all of the above, each process data memory 10, 11, 12, 13 is divided as shown in FIG. Each scanning device 40 and 41 is also capable of performing data transfer between the process control object 60 and the process data memory 12, 13, respectively.

In this state, for example, if the computer I sets data in the transmission area E, each scanning device 40, 41 transfers the data set in the transmission area E. Therefore, the transfer control device 47 in each scanning device 40.41 transfers the control signal to the process control target 60 via the process input/output device 50.51.

For transfer in the reverse direction, the transfer control device 47 writes the process data of the process control target 60 into the transmission areas G and H of the process data memories 12 and 13, and transmits them to the areas g and h of the computers 1 and 2. , the computer side can freely use the process data. If the process data memories 10, 11, 12, and 1.3 are set as shown in Figure 4, each computer 1 and 2 will have all the process data, and there will be no need for data communication between the computers. The burden of this will be reduced.

〔Effect of the invention〕

According to the present invention, each computer has all the data of the controlled objects of the process input/output device, so that necessary data can be acquired by referring to its own memory. Therefore, inter-computer data communication for data acquisition is not required, improving system responsiveness and control performance.

To acquire data from a process control target, the address on the process input/output control device of the data to be acquired and the address on the memory where the data is stored are simultaneously accessed in an orderly manner and transmitted at a predetermined period by cyclic communication.

By making the period sufficiently shorter than the rate of change of the process, the latest data can be obtained with the required accuracy.

Since the computer is not directly connected to the process control equipment,
System construction is improved, the process control device can be separated for maintenance, and maintainability is also improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of a process control system according to the present invention, and FIG. 2 shows a more detailed configuration of the computer, process data memory, and memory control device of the embodiment in FIG. 3 is a block diagram showing the detailed configuration of the scanning device of the embodiment shown in FIG. 1; FIG. 4 is a diagram illustrating a cyclic communication command transfer method and a process data transfer method; FIG. 6 is a diagram showing an embodiment of the structure of command data according to the present invention, and FIG. 6 is a flowchart showing a processing procedure for command capture and command execution by the scanning device of the embodiment of FIG. 1. 1.2... Computer, 10-13... Process data memory, 20-23.
...Memory control device, 30-33...Communication control device, 40.41...Scan device, 42...Processing device, 43...Program data memory, 44...Address memory, 45... - Direction memory, 46... Counter, 47... Transfer control device, 50.51... Process input/output device, 60... Process control object, 70... Communication path, 83... Address bus, 84 ...Data bus.

Claims (1)

[Scope of Claims] 1. A plurality of communication control devices each connected to a control computer or a process control device are connected to a transmission path, and process data is cyclically transmitted from at least one of the communication control devices, and the transmission In a process data processing system in which a communication control device other than a side communication control device includes a data transmission means for receiving the process data, the computer includes a means for inserting and transmitting a control command and control data in cyclic frame data. The process control device has a communication control device connected to the process input/output means and the process input/output means.
A process data processing system characterized by comprising means for executing control contents based on the control command and the control data included in received frame data, and transmitting a control result by inserting the control result into the frame data as a response. 2. The process data processing system according to claim 1, wherein the control command execution means includes means for ignoring the control command when the control command identification number included in the frame data is the same as the previous control command. A process data processing system characterized by: