JPH05122292A - Communication malfunction processing method - Google Patents

Abstract

PURPOSE:To continue the automatic operation even when a communication malfunction occurs by keeping reception data just before the occurrence of the malfunction till a communication malfunction is recovered when a process controller on a receiver side recognizes the communication malfunction and implementing data processing succeedingly by the latched data. CONSTITUTION:A CPU 2 receives data Ai of a side of a CPU 1 and gives the data to a data processing section. When a communication malfunction occur, the CPU 2 resets a flip-flop 4 corresponding to the communication error. When the flip-flop 4 is reset, a changeover device 5 keeps preceding output data. The changeover device 5 sends the latched data to a processing section, in which the processing is continued. Thus, even when the communication malfunction occurs, the automatic operation is continued on a side of the CPU 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication error processing method for recognizing a communication error condition in a distributed digital process control device and appropriately supplying received data to a data processing unit of a receiving device.

[0002]

2. Description of the Related Art Data is transmitted and received by processing of a CPU between devices associated with each other in a distributed digital process control device. By the way, conventionally, when a communication abnormality occurs in such a system, the safety of the plant is ensured by shifting the related control device to the manual mode.

[0003]

However, it is desirable to continue automatic operation as much as possible even when communication is abnormal. This is because, in the manual mode, the plant may be adversely affected by an operator's operation error, etc., and in the current situation of labor saving and sophistication of the control device, it may be difficult for the operator to manually operate. is there.

On the other hand, even if the received data is held at a value before that for a predetermined time, there are many cases in which there is no particular problem.
The present invention has been made in view of these points, and an object of the present invention is to provide a communication abnormality processing method that eliminates operator work as much as possible during communication abnormality and abnormality recovery.

[0005]

In order to achieve the above object, a communication error processing method according to a first aspect of the present invention is directed to a receiving side device when a communication error state occurs between distributed digital process control devices. Is a communication error processing method for the data processing unit of
When the process control device on the receiving side recognizes the communication abnormality, the received data immediately before that is held until the communication abnormality is recovered, and the data processing unit continuously performs the data processing based on the held data.

Further, in the communication abnormality processing method according to the second aspect, when a communication abnormality state occurs between the distributed digital process control devices, the data processing unit of the reception side device continues to perform appropriate data processing. This is a communication error processing method for the case where the process control device on the receiving side recognizes a communication error, the received data immediately before that is held until the communication error is recovered, and the data processing unit continues based on this held data. When the data processing is performed and the process control device on the receiving side recognizes the abnormal recovery, the held data is compared with the new received data, and when the new received data is different from the held data by a predetermined value or more, The data supplied to the data processing unit is changed at a predetermined change rate to gradually approach the original received data.

[0007]

When the process control device on the receiving side recognizes a communication error, the received data immediately before that is held until the communication error is recovered, and the data processing unit stores this stored data. Based on this, data processing is continued. Therefore, according to the present invention, even if a communication abnormality occurs, the automatic operation can be continued.

It should be noted that how the abnormal recovery is recognized is not particularly limited, but for example, when the operator sets the transmitting side device to the automatic mode, the abnormal recovery is performed on the receiving side based on this. May be recognized, and then special work for recovering communication function is unnecessary. [Communication Abnormality Processing Method of Claim 2] When the receiving side process control device recognizes the communication abnormality, the received data immediately before that is held until the communication abnormality is recovered, and the data processing unit continues based on the held data. Data processing,
When the process control device on the receiving side recognizes the abnormal recovery, the held data is compared with the new received data,
If the new received data differs from the held data by a predetermined value or more, the data supplied to the data processing unit is changed at a predetermined rate of change to gradually approach the original received data.

Therefore, during the transition period when the communication line returns to normal, the data supplied to the data processing unit does not change significantly. It should be noted that how to recognize the abnormal recovery is not particularly limited, but for example, when the operator sets the transmitting side device to the automatic mode, the receiving device side recognizes the abnormal recovery based on this. However, if so, special work for restoring the communication function is unnecessary.

[0010]

The present invention will be described in more detail based on the following examples. [Embodiment 1] FIG. 1 is a functional block diagram showing an embodiment of the present invention. This block diagram shows a state in which the CPU 1 of the transmission side device and the CPU 2 of the reception side device are connected via the communication bus 3. The receiving side device is provided with a flip-flop (FF) 4 which is reset at the time of communication error and is set at the time of error recovery, and a CPU.
There is provided a switch (T) 5 for receiving the transmission data A _i transmitted from the communication bus 1 via the communication bus 3 and supplying the transmission data A _i to a data processing unit (not shown).

The output of the flip-flop 4 is supplied to the switch 5, and the switch 5 supplies the transmission data A _i from the CPU 1 to the data processing unit as it is when the flip-flop 4 is in the set state. If the pull-up 4 is in the reset state, the output data before that is held. In addition, in the case of this embodiment, the flip-flop 4 and the switch 5 are represented by hardware, but they are actually processed by a program.

The operation of the apparatus of the first embodiment will be described below with reference to FIG. The CPU 2 receives the data A _i on the CPU 1 side according to a predetermined communication protocol, and supplies this data to the data processing unit. However, when a communication error occurs for some reason, the CPU 2 resets the flip-flop 4 in response to this communication error. Specifically, for example, the data in the memory address for the flip-flop is set to 0.

The switch 5 is a part which operates to supply the data A _i received from the communication bus 3 to the data processing part. When supplying the received data to the data processing part,
The output of the flip-flop 4 is referred to. Specifically, for example, the data value of the memory address for the flip-flop is 0
Check whether or not. Assuming that a communication error has occurred, the switcher 5 recognizes from the data value of the flip-flop 4 that a communication error has occurred, and outputs the same data as before (hereinafter referred to as hold data). Supply to the processing unit.

Therefore, even if a communication error occurs, the CP
On the U2 side, automatic operation will be continued. still,
Since the hold data is supplied to the data processing unit, it cannot be said that the operation is the same as in the normal state, but there are cases where supplying the same data as before does not cause a problem. It works effectively. Eventually, when the communication abnormality is recovered, the flip-flop 4 is set corresponding to the recovery of the communication line (for example, data other than 0 is stored in the memory address for the flip-flop). Then, the switch 5 returns to a normal operating state thereafter,
The data A _i received from the transmitting CPU 1 is supplied to the data processing unit as it is.

When the CPU 1 side recovers to the normal state, the operator usually confirms the fact and then sets the system to the automatic mode. However, the CPU 2 confirms the signal accompanying this setting as the final normality. You may make it receive as a signal and set the flip-flop 4. [Embodiment 2] FIG. 3 is a functional block diagram showing an embodiment of the present invention. The feature of this embodiment is that the switching device 5
Next to the change rate setter (RG) 6 and deviation monitor (MO)
7 is provided. The flip-flop 4 is C
It is configured to be set by an automatic signal transmitted from PU1.

The change rate setting unit 6 is a part which operates only at the beginning of the communication error recovery, and compares the data value A _{i at the} beginning of the error recovery with the hold data value A ₀ before that, and both of them are set to predetermined values. If the difference is above, the output value is changed at a constant rate. In the case of this embodiment, the change rate setting device 6 and the deviation monitor 7 are realized by programs, but they may be configured by hardware.

The operation of the apparatus shown in FIG. 3 will be described below from the occurrence of a communication error to the recovery of the communication error. CPU
2 receives the data A _i on the CPU 1 side according to a predetermined communication protocol and supplies the data A _i to the data processing unit. However, when a communication error occurs, the flip-flop 4 is reset accordingly. ..

Then, the switching device 5 causes the flip-flop 4 to
Recognizing that a communication error has occurred from the data value of,
After this, the same data as before (hold data)
Is supplied to the data processing unit. That is, by continuously supplying the hold data, the automatic operation mode is continued. Eventually, when the CPU 1 side returns to normal, the operator confirms the fact and then sets the system to the automatic mode. In the case of the embodiment shown in FIG. 3, the set signal (automatic signal) is inputted to the flip-flop 4 in response to this setting operation by the operator, and thereafter, the switching device 5 uses the data A from the CPU 1 side. _i is output as is.
That is, in this embodiment, the operator's setting to the automatic mode (automatic signal) is used as the final normality confirmation signal, and the communication line is automatically restored without requiring any special confirmation work. Become.

However, the transmission data A _i from the CPU 1
If the data A _i is supplied to the data processing unit as it is, if the data A _i is significantly different from the level of the hold data A ₀ , the control amount to the controlled object may change suddenly. Therefore, the change rate setting unit 6 and the deviation monitor 7 appropriately control the data supplied to the data processing unit in the transitional period after recovery of the communication error as follows.

That is, the rate-of-change setter 6 uses the hold data A ₀ and the data A _i when the communication error is recovered (see FIG. 2).
If the two data are different from each other by a predetermined value or more, the output of the change rate setting unit 6 is constantly changed from the level of the hold data A _{0 to} the level of the newly received data A _i. Rate (see T _{1 to} T _{2 in} FIG. 2). On the other hand, the deviation monitor 7 monitors the input and output values of the change rate setting device 6, and stops the operation of the change rate setting device 6 when the output value of the change rate setting device 6 matches the input value. After that, the output of the switch 5 (this is nothing but received data from the CPU 1) is directly supplied to the data processing unit (RG quick operation in FIG. 2).

In the above description, the case where there are two CPUs has been taken as an example, but the present invention does not limit the number of CPUs.

[0022]

As described above, according to the communication abnormality processing method of the first aspect, even if a communication error occurs, automatic operation is possible after that, and the operator's burden is reduced. In addition, the safety to the plant can be maintained as much as it does not require the operator's operation. Further, in addition to the above effects, the communication error processing method according to claim 2 can resume data transmission / reception without requiring special inspection work such as checking signal data even when a communication error is recovered, and an error occurs. There is no fear of sudden changes during recovery.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the invention of claim 1;

FIG. 2 is a diagram illustrating a change in data supplied to a data processing unit when a communication error is recovered in the device of FIG.

FIG. 3 is a block diagram showing an embodiment of the invention of claim 2;

[Explanation of symbols]

 FF flip-flop T data switch

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Claims (2)

[Claims] 1. A communication error processing method for allowing a data processing unit of a receiving side device to continue appropriate data processing when a communication error condition occurs between distributed digital process control devices. When the process control device on the side recognizes a communication error, the received data immediately before that is held until the communication error is recovered, and the data processing unit continues to perform data processing based on this held data. Processing method. 2. A communication error processing method for allowing a data processing unit of a receiving side device to continue appropriate data processing when a communication error condition occurs between distributed digital process control devices. When the process control device on the receiving side recognizes a communication error, the received data immediately before that is held until the time when the communication error is recovered, and the data processing unit continues to perform data processing based on this held data. When the abnormal recovery is recognized, the held data is compared with the new received data, and when the new received data is different from the held data by a predetermined value or more, the data to be supplied to the data processing unit is predetermined. The communication abnormality processing method is characterized in that it is changed at a rate of change to gradually approach the original received data.