JPH01154202A - Duplex process controller - Google Patents

Abstract

PURPOSE:To assure the simultaneous property of the control arithmetic actions, etc., by transmitting the arithmetic end signal of one of two systems when the arithmetic operation of the other system is through and performing the collation between both systems in response to said arithmetic end signal to send back the result of the collation in a duplex process control system. CONSTITUTION:Two systems A and B are kept under the control and holding states respectively. When the arithmetic operation is through with the system A, this end state is transmitted to a diagnosing part 2B of the system B by means of an interlock signal 13B. Receiving the signal 13B, the system B performs the collation of arithmetic results between both systems. When this collation is over, the system B transmits an interlock signal 13A showing the end of collation to the system A. Both systems receive the collation end signals respectively and carry out the arithmetic operations of the following cycles. Thus both systems start the control arithmetic in the same timing and therefore assure the simultaneous property of both arithmetic results despite the transient changing state of a plant 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a process control device with a duplex configuration that is applied to general process control.

[Conventional technology]

FIG. 2 is a block diagram of a conventional duplex process control device described in, for example, Japanese Unexamined Patent Publication No. 59-2162.

In the same figure, (IA) is an A-system calculation unit, and (IB) is a B-system calculation unit.
The arithmetic unit of the system, (2A) is the diagnostic unit of the A system, and (2B) is the diagnostic unit of the B system. Diagnosis department (2A), (
From 2B), the diagnosis results for each system (3A),
(3B) is output to the switching relay (4). In addition, the operation outputs of each system are output from the calculation units (IA) and (IB) as operation outputs (5A) and (5B), respectively, to the contacts of the switching relay (4), and the diagnostic results (3A) and
(3B) is switched by the switching relay (4),
The final output (6)) is sent to the plant (7).

Each output from the plant (7) is an input signal (8A)
, (8B) as the arithmetic unit (IA), (IB>
is supplied to Further, the final output (6) is supplied to the calculation units (IA) and (IB) as readback input signals (IOA) and (IOB), respectively. Diagnosis department (2A
), and from (2B) is a status signal (lla) indicating the current state of each system.

fllb) is output and supplied to the relay part (12).

Next, the operation will be explained. The A system calculation unit (18) and the B system calculation unit (IB) receive input signals (
88) and (8B) and execute the same control calculation. Then, one of the systems outputs the calculation result to the process.

On the other hand, the final output (6) of the control device is given to the plant (7), and at the same time the A system calculation section (IA) and the B system calculation section (IB
) also has a readback signal (IOA), (li)
be reread as. Here, the standby system compares this readback signal with its own calculation result and detects whether there is a mismatch. Suppose that the standby system is B system and the B system diagnosis section (2
If it is determined that B) does not match, a status signal (IIB) indicating the mismatch is sent to the relay part (12) to notify the outside that a failure has occurred in either one of the duplex systems.

[Problem that the invention seeks to solve]

Since the conventional duplex process control device is configured as described above, the simultaneity of calculations in the A system and the B system cannot be guaranteed. Therefore, when the plant is undergoing transient changes, the calculation results of the A system and the B system often do not match, and problems have been raised, such as the system switching occurring too quickly.

This invention was made to solve the above-mentioned problems, and even when the plant is undergoing transient changes, the A system and B system
It is an object of the present invention to provide a redundant process control device that can guarantee the simultaneity of system calculation results and prevent unnecessary system switching.

[Means for solving problems]

In the duplex process control device according to the present invention, two calculation systems are duplicated for the process and execute the same control calculation, one of the systems outputs the calculation result to the process, and the other system outputs the calculation result to the process. In a duplex process control device in which the system compares the result with its own calculation result and detects whether there is a discrepancy, when the one system finishes the calculation, it sends a signal of completion of the calculation to the other system. the first means and the other system collate the calculation results in response to the calculation end signal;
and second means for sending a signal indicating completion of verification to the one system after completion of verification.

(Operation) In this invention, the first means
Sends a computation end signal to the system. And the second means is
Upon receiving this signal, the calculation results are compared, and when the comparison is completed, a completion signal is sent back to the A system. Then, the A system and the B system simultaneously start executing the next synchronization calculation, and an interlock signal is added between the two systems, thereby guaranteeing the simultaneity of the A system and B system, and removing unnecessary systems. Switching can be prevented.

(Example) An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a block diagram of a duplex process control device showing one embodiment of the present invention.

Components that are the same as those of the conventional device shown in FIG. 2 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In this invention, the interlock signal (13A) for guaranteeing the simultaneity of calculations in the A system and the B system is transmitted to the A system diagnostic section (2).
The interlock signal (13B) is connected between the A system calculation unit (IA) and the B system diagnostic unit (2B) between the A system calculation unit (IA) and the B system calculation unit (IB).
).

The A-system calculation section (IA) and the B-system calculation section (IB) read input signals (8A) and (8B) from the plant (7) and each execute the same control calculation. Now, assume that system A is in control and system B is in standby mode. When the calculation of A system is completed, use the interlock signal (13B) to
Informs the system diagnosis unit (2B) that the calculation of system A has finished.

The B system receives this interlock signal (13B), collates the calculation results, and when the collation is completed, conversely transmits an interlock signal (13A) indicating the completion of the collation to the A system.

The A system and the B system receive this verification end signal and execute the calculation for the next cycle. As a result, the A system and the B system start control calculations at the same timing, and even if the plant (7) is undergoing a transient change, the simultaneity of the calculation results can be guaranteed.

If the calculation results do not match, the relay part (12) is operated based on the status signal (IIB), and the fact that a failure has occurred in one of the duplex systems is transmitted to the outside. In the above-described embodiments, the case where at least one system is operating normally has been described, but it is also necessary to consider the case where one system is in failure.

In this case, the interlock signal (1
It is necessary to prevent 3A) and (13B) from adversely affecting a healthy system. For this reason, a timer is monitored on the signal receiving side, and if a response signal is not returned after a certain period of time, calculations for the next cycle are started.

By doing so, even if one system fails, control can be continued with the other system.

〔Effect of the invention〕

As explained above, according to the present invention, when one system completes an operation, the first system sends an operation end signal to the other system.
Since the second means performs verification in response to the calculation end signal and sends back the verification results, it is possible to guarantee the simultaneity of the control calculations.

Therefore, there is an effect that a stable duplex process control device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of a duplex process control device according to an embodiment of the present invention, and FIG. 2 is a block configuration diagram showing the configuration of a conventional duplex process control device. (IA) is the A system calculation section, (IB) is the B system calculation section, (2A
) is the A-system diagnostic section, (2B) is the B-system diagnostic section, (3A) is the A-system diagnostic section.
System diagnosis result, (3B) is B system diagnosis result, (5A) is A thread operation output, (5B) is B thread operation output, (6) is final output, (7) is plant, (8A), (aa ) is the input signal from the plant, (IOA) and (10B) are the readback signals, (IIA) and (IIB) are the status signals, (12) is the relay part, (13A) is the A system interlock signal, ( 13B) is a B-system interlock signal. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] Two calculation systems are duplicated for a process and execute the same control calculation, one of the systems outputs the calculation result to the process, and the other system compares this with its own calculation result. In a duplex process control device for detecting a mismatch, the first means sends a computation end signal to the other system when the one system finishes computation, and responds to the computation end signal. and a second means for collating the calculation results by the other system and sending a signal indicating completion of the collation to the one system after the collation is completed.
Heavy duty process control equipment.