JPS62186301A - Backing-up circuit for controller - Google Patents

Abstract

PURPOSE:To multiplex a controller and to execute the backing-up between controls without using a special changing-over circuit by controlling the output prohibiting condition of a serial transmitting circuit of plural controllers in accordance with the execution/standby and normality/abnormality of the controller. CONSTITUTION:When an abnormality occurs at a loop controller 3a of an executing condition, the loop controller 3a transfers the abnormality to a loop controller 3b of a standby condition and makes its own serial transmitting circuit into an output prohibiting condition. When the loop controller 3b detects the abnormality of the loop controller 3a, the output prohibiting condition of its own serial transmitting circuit is released, and an analog input and an MV output command are transmitted to an instrumentation ambient interface device 8. In such a case, since the loop controller 3b synchronizes and calculates the loop controller 3a even during the standby, the loop controller 3b continues the control in succession to the loop controller 3a.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a backup circuit for controllers 1 to rollers that can multiplex controllers with a simple configuration.

``Technical Background of the Invention and HJI Points'' A general system configuration of a loop controller for instrumentation control is shown in FIG.

FIG. 5 shows the case of controlling the discharge flow rate of the pump, in which the discharge flow rate of the pump 1 is detected by the flow meter 2 as a process value Pv, and is input to the loop controller 3 and the display setting device 5.

Loop controller 3 is an analog input circuit.

It is composed of a digital output circuit, a serial transmission circuit, and a microcomputer that controls these, and converts the process value Pv and pump 1 operation: jLMV into digital values through an analog input circuit and inputs them, as well as a serial transmission line. It exchanges information with the display setting device 5 via the MV output device 6, and outputs an output increase/decrease command to the MV output device 4.

The display setting device 5 includes a display circuit using a bar graph LED, a setting circuit using a key switch, an analog input circuit,
It is composed of a digital output circuit, a serial transmission circuit, and a microcomputer that controls these, and sends the setting value sv from the setting circuit to the loop controller 3 via the serial transmission line 6.

The loop controller 3 performs a PID calculation between the process value Pv and the set value Sv, and controls the discharge flow rate of the pump 1 by giving an increase/decrease command to the correction output device 4 so that PV matches Sv.

The manipulated variable MV and the process value Pv are also input to the display setting device 5 via the analog input circuit, and are displayed together with the set value SV.

The operation of the loop controller 3 has an automatic mode and a manual mode. In the automatic mode, the manipulated variable MV is controlled by the loop control described above, and in the 1-manual mode, the manipulated variable MV is increased or decreased by manual operation from the display setting device 5.

In FIG. 6, the loop controller 3 shown in FIG. 5 is duplicated, and two loop controllers 3a and 3b are provided to perform backup operations for each other.

In FIG. 6, a duplicated loop controller 3a
, 3b are programmed with the same control program, and the programs are executed in synchronization.

In addition, both loop controllers 3a and 3b are given the same process value Pv, operation: jfMV, and set value Sv, and output increase/decrease commands to the MV output device (from either loop controller via the switching circuit 7) are given to both loop controllers 3a and 3b. Output.

A switching command to the switching circuit 7 is given from both loop controllers, and switching is performed to the loop controllers 1 to rollers that are in operation.

In addition, both loop controllers mutually detect normal/abnormal signals, and when an abnormality occurs in the operating loop controller, the standby loop controller detects this and switches the switching circuit 7 to the standby side. This performs a backup operation.

However, in the conventional backup circuit described above, the switching circuit 7 switches multiple signal lines to the MV output device, and analog signals for the process value Pv and operation amount are also added, so the number of signal lines increases. , there is a problem that the circuit becomes complicated.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a controller backup circuit that does not require a switching circuit even when loop controllers are multiplexed, and whose configuration is simple even when one loop controller is backed up by multiple controllers. .

[Summary of the invention]

The present invention provides a plurality of controllers each having a serial transmission circuit that can set the output to a high impedance state and inhibit output, a peripheral interface device having a display setting circuit, an input/output circuit, and a serial transmission circuit, and a plurality of controllers and peripherals. A serial transmission line is provided for transmitting signals between the interface devices, and output inhibition states of the serial transmission circuits of the plurality of controllers are controlled according to execution/standby and normal/abnormal status of each controller.

This is a controller backup circuit that multiplexes controllers and enables backup between controls without using a special switching circuit.

[Embodiments of the invention]

An embodiment of the present invention is shown in FIG.

In FIG. 1, 1 is a pump, 2 is a flow meter, and 3a.

3b is a loop controller, 8 is an instrumentation peripheral interface device, and 6 is a serial transmission circuit. Each of the loop controllers 3a and 3b is equipped with a serial transmission circuit that can set the output to a low impedance and inhibit the output. The instrumentation peripheral interface group W18 is equipped with a serial transmission circuit 2 indication setting circuit, an MV output operation circuit, and an analog input circuit, and the loop controllers 3a and 3b synchronously execute the same program.
A redundant system is constructed by backing up each other.

When the loop controller 3a is in the execution state and the loop controller 3b is in the standby state, the loop controller 3a
If it is normal, the normality is transmitted to the loop controller 3b, and the loop controller 3b puts its own serial transmission circuit in an output inhibit state, and the loop controller 3a in the normal state connects the instrumentation peripheral via the serial transmission circuit 6. It sends analog inputs and MV output commands to the interface device 8, and receives from the instrumentation peripheral interface device 8 the automatic/manual mode of the setting circuit, the set value Sv and process value Pv, and the analog input of the operating device MV.

At this time, the loop controller 3b in the standby state also receives the signal from the instrumentation peripheral interface device 8 at the same time, and is in the same control state as the loop controller 3a in the execution state.

If an abnormality occurs in the loop controller 3a in the running state, the loop controller 3a notifies the abnormality to the loop controller 3b in the standby state, and also puts its own serial transmission circuit in an output inhibit state.

When the loop controller 3b detects an abnormality in the loop controller 3a, it releases the output prohibition state of its own serial transmission circuit and sends analog input and MV output commands to the instrumentation peripheral interface device 8.

In this case, since the loop controller 3b performs calculations in synchronization with the loop controller 3a even during standby, the loop controller 3b continues to control the loop controller 3a.

Figure 2 shows the functional configuration of the instrumentation peripheral interface unit gt8, which includes a microcomputer (CPU) 4
1 executes the program in the ROM 42 and transmits the serial transmission circuit (DTR) from the loop controller 3Q or 3b.
According to the analog input and MV output command obtained through 44, the process value Pv is output from the analog input circuit (AI) 46.
, convert the operating value MV to a digital value and input it, MV
The MV output circuit (MVO) 45 is operated so as to output the manipulated variable value specified by the output command.

In addition, the switch status is input from the setting circuit (SET) 48, stored in the RAM 43, and calculated to determine the automatic/manual mode, set value SV, and manual operation status in manual mode. Operated in automatic/manual mode, set value Sv is analog input process value P
v and the operating value MV are sent to the loop controller 3a or 3b via the serial transmission circuit 44.

Furthermore, the set value Sv, process value P■, manipulated variable setting V, and automatic/manual mode are sent to a display circuit (DISP) 47 and displayed on the LED.

Another embodiment of the invention is shown in FIG.

FIG. 3 shows a case where there are three or more loop controllers and one loop controller is backed up by two or more loop controllers.

In FIG. 3, each of the loop controllers LCI to LCn has a serial transmission circuit with an output prohibition function, and a normal signal or an abnormal signal is inputted sequentially, and when a normal signal is inputted, the loop controller on standby continues to be on standby. When an abnormal signal is input, it determines whether it is normal or abnormal, and when it is normal, it moves to the execution state and outputs a normal signal, and when it is abnormal, it continues to standby and outputs an abnormal signal. Therefore, for example, when the loop controller LCI is normal and in the execution state, all of the LC2 to LCn are in the standby state.

If an abnormality occurs in the loop controller 14C1, the LC2 receives this abnormality signal and determines whether it is normal or abnormal, and if it is normal, it enters the execution state, receives and continues the control of the LCI, and outputs a normal signal. The loop controllers after LC3 are placed in a standby state. In this case L
When C2 itself is also abnormal, it continues in a standby state and outputs an abnormal signal.

This abnormality signal is input to the next loop controller LC3, which performs the same determination and sequentially performs backup.

Next, FIG. 4 shows an embodiment in which the present invention is applied to a multi-loop controller.

In FIG. 4, numeral 9 denotes a multi-loop controller that controls a plurality of loops, and is connected to a plurality of instrumentation peripheral interface devices W18 each having a serial transmission circuit that can inhibit output.

An identification number corresponding to each instrumentation peripheral interface device V118 is added to the analog input and MY output commands output from each loop of the multi-loop controller.

Each instrumentation peripheral interface device 8 always keeps its own serial transmission circuit in a state where output is prohibited, and receives analog input from the multiloop controller 9.

Only when the identification number of the V output command matches the own identification number, the output prohibition state is canceled and the analog input values of automatic/manual mode, set value SV, process value Pv, and operating value MV are returned. and is connected to the multiloop controller 9.

Also, both loops of the multi-loop controller 9 execute the same control program synchronously, one is in the running state and the other is in the standby state, and when the loop in the running state is abnormal, the output of the other loop in the standby state is prohibited. Since the state is canceled and the state is moved to the running state, backup can be performed.

〔Effect of the invention〕

As explained above, according to the present invention, by providing a serial transmission circuit that can inhibit output, even if the loop controller is duplicated and backed up, there is no need for a switching circuit, and a single loop controller can be operated with a relatively simple configuration. can be backed up by multiple loop controllers,
Furthermore, a rational controller backup circuit that can be applied to a multi-loop controller can be obtained.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing one embodiment of the present invention, and Fig. 2 is a system diagram showing an embodiment of the present invention.
3 and 4 are system diagrams showing other embodiments of the present invention, and FIG. 5 is a general diagram of an instrumentation control device including a loop controller. FIG. 6 is a system diagram showing an example of a conventional backup circuit. 1 Pump 2 Flowmeter 3, 3a, 3b, LCI to LCn Loop controller 4 MV output device 5 Display setting device 6 Serial transmission path 7 Switching circuit 8 Instrumentation peripheral interface device 9
Multi-loop controller (8733) Agent Patent attorney Yoshiaki Inomata (and 1 other person) Figure I Figure 2 "--m---=-J" Figure 4 Figure 4 $5 Figure 6

Claims (1)

[Claims] A plurality of controllers each having a serial transmission circuit that can set the output to high impedance and inhibit output, a peripheral interface device having a display setting circuit, an input/output circuit, and a serial transmission circuit, and a connection between the plurality of controllers and the peripheral interface device. What is claimed is: 1. A backup circuit for a controller, comprising a serial transmission path for transmitting signals, and controlling the output inhibited state of the serial transmission circuits of the plurality of controllers according to execution/standby and abnormality of each controller.