JPH0124398B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plant control device, and more particularly to a plant control device using a so-called distributed control system in which control functions are distributed for each loop.

In recent years, with the advancement of microcomputers, in the field of plant control, instead of conventional analog controllers, microcomputers are installed in controllers, and plant one-loop (digital control points or analog control points are controlled). did)
Distributed control systems that control each location are being adopted. A plant control device using this distributed control system consists of multiple controllers (hereinafter simply referred to as controller stations) each with a built-in microcomputer.
and a display device (hereinafter simply referred to as a display station) for performing centralized monitoring operations using a CRT or the like are connected via a communication path, and communication control between each station is performed.

By the way, as a communication control method for a plant control device using a conventional distributed control system,
There is something called a data freeway, which is a ring-shaped communication path.

In this data freeway, a communication control device that performs communication control management is provided on a communication path, and communication between each controller station and a display station is performed via this communication control device. In this type of communication control method,
Since a dedicated communication control device is required, the entire system is not expandable, which not only reduces communication efficiency but also reduces reliability.

Therefore, the present invention provides a plant control system that allows each station to communicate equally without connecting a dedicated communication control device to the communication path, is highly reliable, has excellent expandability, and can be easily implemented as an LSI. The purpose is to provide equipment.

In the present invention, a microcomputer is installed in the one-loop control controller station and display station connected to the communication path, a common communication interface circuit and a self-diagnosis circuit are provided in each station, and each station is controlled by the microcomputer. A backup station is provided which communicates equally with the controller station and the display station and has a communication interface circuit and a self-diagnosis circuit, and each of the self-diagnosis circuits transmits its diagnosis results to other stations via the communication path. At the same time, when the diagnosis result detects a failure of the own station, the own station is disconnected from the communication path,
The backup station receives the diagnosis result from the communication channel, determines a failed station, and executes control of the target plant in place of the failed station. A further object of the present invention is to develop the invention for a dual-system circular communication path.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

FIG. 1 is a diagram showing the overall configuration of a plant control device that is an embodiment of the present invention. In the figure,
One-loop control controller stations 1 and 2 each containing a plurality of microcomputers control the plant 3 via plant operation signals 21 and 22, respectively. On the other hand, controller station 1 has transmitting/receiving signal line 1
It is connected to communication paths 7a, 7b via switches 7a, 17b and switches 9a, 9b. Here communication path 7
a, 7b consist of two sets of communication paths 7a and 7b to constitute a duplex system. For ease of understanding, a and b used in this explanation refer to two sets of communication paths 7a and 7.
It corresponds to b.

Further, the controller station 2 is also connected in the same way as the controller station 1.

Furthermore, the display station 5 is connected to the transmission/reception signal line 1 on the communication path 7.
7a, 17b and switches 9a, 9b. The display station 5 causes the display device 6 to display the plant status via the display signal 23, and key-in data input to the display device 6 is sent to the display station 5.

In addition, when one of the multiple control stations fails, the plant 3 is controlled in place of the failed station N:1
Backup station 4 also transmits and receives signal lines 17a and 17b.
and communication paths 7a, 7 via switches 9a, 9b.
connected to b.

Switches 9a and 9b connected to each station are controlled by switch drive signals 19a and 19b.

The controller station 1 includes a communication interface circuit 11 that manages communication control, self-state diagnosis, and switch drive signals 19a and 19 for switches 9a and 9b.
The control circuit 13 includes a self-diagnosis switching/disconnecting circuit 12 that controls the plant 3, a plant control circuit 14 that controls the plant 3, and a microcomputer that controls these as a whole. Controller station 2 is similarly configured. Among these, the communication interface circuit 11, the self-diagnosis switching/disconnecting circuit 12, and the control circuit 13 are common circuits that are common not only to the controller stations 1 and 2 but also to the N:1 backup circuit 4 and the display station 5. The N:1 backup station 4 receives a plant operation signal 2 for replacing a failed station in addition to the circuit group consisting of the controller stations 1 and 2.
It has a switching circuit 15 that switches between 1 and 22.

The display station 5 includes a display control circuit 16 in addition to common circuits 11, 12, and 13. Each station 1, 2, 4, 5
, various circuits are mounted on a single printed board.

The connections between the communication path 7a, the switch 9a, and each station will be explained with reference to FIG. The other contacts 33 are connected to transmission data 35a from each station, and a switch state signal connected to one of the two contacts 32, 33 is transmitted to the communication path 7a to the lower station. When the switch drive signal 19a from each station is in a "bypass state", when each station is absent, or when the power of each station is off, the switch 31 is electrically connected to the contact 32 side, and the communication path 7a is placed in a bypass state. On the other hand, when the switch drive signal 19a is in the "on" state, conduction occurs to the contact 33 side, transmission data from the upper station is received by each station, and transmission data from each station is transmitted to the lower station via the communication path 7a. Ru. Note that the communication path 7b, switch 9b, and connections with each station are the same as in FIG.

An example of the control circuit 13 will be explained with reference to FIG. 3. It includes a microcomputer 41, a program memory 42, a data memory 43, an input/output interface circuit 44, a data line 45, and an address line 4.
6 and a control line 47, and the microcomputer 41 executes overall control of each station. Program memory 42 and data memory 43
N:1 includes communication control, switch control, and self-diagnosis functions that are common to each station, and functions specific to each station, that is, plant control functions for controller stations 1 and 2.
The backup station 4 stores a plant switching function and a plant control function, and the display station 5 stores programs and data regarding a display control function.

The interface circuit 44 is connected to the self-diagnosis switching circuit 12 and the switching circuit 1 in the N:1 backup station 4.
The input/output control signal 48 that controls the input/output signal 5 is controlled.

Data lines 46, address lines 45 and control lines 47 are used to control circuits not shown in FIG. For example, communication interface circuit 1
Connected to 1.

In this embodiment, the control circuit 13 includes a microcomputer 41, a program memory 42, a data memory 43, an input/output interface circuit 44, a data line 46, an address line 45, and a control line 47.
However, as long as the circuit has the above-mentioned functions, for example, a one-chip microcomputer may be used without detracting from the effects of the present invention. The circuit may include all or part of the functions of the circuit 12.

Next, the communication interface circuit 11 will be explained with reference to FIG.
Communication channel selection signal 6 for selecting one of the communication channels with
1, one of the received data is selected and connected to the other input of the selector 52 via the selector 52 and shift register 55. The selector 52 selects one of the two input signals based on the GA station signal 60. This means that a station that has the transmission right (GA) of the communication channel receives received data delayed by a certain period of time via the shift register 55, while a station that does not have the transmission right of the communication channel receives the received data that is the output of the selector 51. The received data 57 of the communication control circuit 56 is selected.

The communication control circuit 56 is a circuit that has the function of executing HDLC (High Data Link Controller) or SDLC (Serial Data Link Controller) procedures that are standardized in communication control, and controls settings for communication control, transmission/reception data, and microcomputer. The connections are data line 46, address line 4
5 and control line 47.

Transmission data 35a, 35 to communication paths 7a, 7b
b is the output of selectors 53a and 53b. The selector 53a selects the received data 34a and the communication control circuit 5.
It has a function of selecting one of the two input signals of the transmission data 58 from 6 using the off-loop signal 59. Normally, the transmission data 58 from the communication control circuit 56 is selected and becomes the transmission data 35a to the communication path 7a, but when the corresponding station transmits transmission data in response to the received data addressed to itself, the communication path In the off-loop mode when changing the communication state from the on-loop mode to the 1:1 mode via the off-loop mode, the received data 34a from the communication path 7a is selected and used as the transmitted data 35a.

The selector 53b has the same function as the selector 53a, except that the selector 53b inputs the received data 34b instead of the received data 34a and outputs the transmitted data 35b.

The off-loop signal 59, GA station signal 60 and communication path selection signal 61 are sent to the input/output interface circuit 4.
Obtained from 4. However, the off-loop signal 59 and the GA station signal 60 are the same even if they are instructed by the communication control circuit 56.

Next, the switching circuit 15, which is a component of the N:1 backup station 4, will be explained with reference to FIG.
A switching signal 24 from the control circuit 13 of the N:1 backup station 4 becomes an input to the decoder driver 71. The switching signal 24 indicates the address number of the failed station to be backed up and whether or not to back it up. When backing up the control station 1, the plant operation signal 21 is passed through the plant control circuit 14 through the switch 72 and the plant signal 74.
You can connect with Switch 72 is driven by switch drive signal 76. When backing up the control station 2, the switch 73 is turned on and the plant operation signal 22 is connected to the plant signal 74. Switch 73 is driven by a switch drive signal 75. The reason why switches 72 and 73 are used here is that insulation between each station is required, and the same applies to other insulation methods. In a plant control device that does not require insulation between stations, a plant operation signal can be selected for each station using a selector and a decoder.

Next, the self-diagnosis switching/disconnecting circuit 12 will be explained with reference to FIG. The self-diagnosis switching disconnection circuit 12 is
In order to use either of the two sets of communication paths 7a, 7b, one of the switches 9a, 9b is turned on and the other is put in the bypass state, or the control circuit 13 or the communication interface circuit 11 It has a function of self-diagnosing that the corresponding station is out of order and disconnecting the station from both of the two sets of communication paths 7a and 7b.

This is because when the control circuit 13 is normal, it generates a pulse signal that repeats periodically, and both the transmitted data and received data always change within a certain period of time. , 35b, pulse generation circuits 81, 84, 82, 85, 8 that generate pulses every time the control circuit normal signal 89 changes the level of "1" or "0".
3 output signal is used. The pulse generation circuit has a function of outputting a pulse with a fixed time width when there is a level change in the input signal, and outputting a pulse with a fixed time width when the next level change occurs in the input signal within the fixed time width. In other words, if there is a level change in the input signal within a certain period of time, the output of the pulse generation circuit will always be a level pulse, but if an abnormality occurs and there is no level change in the input signal, the output of the pulse generation circuit will be a pulse. will no longer occur.

Further, the switch drive signals 19a, 19b are also obtained by the switch control signals 88a, 88b instructed by the control circuit 13. From the above, the switch drive signals 19a, 19b are
The conditions for turning on 9b are expressed by the following equation.

“On state”=(switch control signal 88)・(control circuit normal)・(receiver signal △

Claims (1)

[Claims] 1. Control is executed by a plurality of one-loop control controller stations each having a built-in microcomputer and controlling the target plant, and the built-in microcomputer in place of one failed station among these controller stations. A communication path that connects a backup station, each controller station, a display station that displays the status of the backup station, and each controller station, backup station, and display station, and communicates between the stations that are given transmission rights in order. Each station has a common communication interface circuit and a self-diagnosis circuit, and under the control of a built-in microcomputer, the communication interface circuit detects the communication path when the transmission right is granted to the station itself. The self-diagnosis circuit communicates with other stations via the communication path, and the self-diagnosis circuit transmits the diagnosis result to the other station via the communication path. 2. A plant control device characterized in that the backup station receives diagnosis results from the communication path, determines a faulty station, and executes control of a target plant in place of the faulty station. 2. A plurality of one-loop control controller stations that have built-in microcomputers and control the target plant, a backup station that executes control using the built-in microcomputer in place of one failed station among these controller stations, and each controller. A communication system configured in a dual system ring, in which a display station that displays the status of stations and backup stations is connected to each controller station, backup station, and display station, and communication is performed between each station that is given the right to transmit in sequence. Each station has a common communication interface circuit and a self-diagnosis circuit, and under the control of a built-in microcomputer, the communication interface circuit selects one communication path and transmits it to its own station. The self-diagnosis circuit communicates with the other station via the selected communication channel when the right is given, and the self-diagnosis circuit selects one communication channel and transmits the diagnosis result, and also detects its own failure as a result of the diagnosis. When detected, it disconnects its own station from the communication channel, and the backup station receives the diagnosis result from the communication channel, determines the faulty station, and executes control of the target plant in place of the faulty station. Features of plant control equipment. 3. The communication interface circuit includes a first selector that selects received data on one side of a dual-system circular communication path, a register that takes in the received data selected by the first selector, and a a second selector that selects the received data of the register when it has the transmission right, and selects the reception data of the first selector as it is when it does not have the transmission right; The self-diagnosis circuit has a communication control circuit that controls the transmission and reception of data, and a third selector that puts the transmission data from the communication control circuit on one of the communication paths, and the self-diagnosis circuit controls the data received from the communication path. A first pulse generation circuit that generates a pulse every time the level changes, a second pulse generation circuit that generates a pulse every time the level of data transmitted to the communication path changes, and a pulse generation circuit that generates a pulse in response to normal operation or failure of the local station. a third pulse generator that generates
Claim 2 further comprising an AND gate for calculating a logical product between the output pulse of the third pulse generator and a control signal for selecting a communication path.
The plant control device described in Section 1.