JP3196256B2 - Communication error handling method for distributed process control device - Google Patents

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 state in a distributed digital process control apparatus and appropriately supplying received data to a data processing unit of a receiving apparatus.

[0002]

2. Description of the Related Art Data transmission / reception is performed by CPU processing between related devices in a distributed digital process control device. By the way, when a communication abnormality occurs in such a system, conventionally, a related control device is shifted to a manual mode to secure the safety of the plant.

[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, there is a risk that the plant may be adversely affected by an operator's operation error or the like, and there are situations where it is difficult to deal with manual operations by the operator under the current situation of labor saving and advanced control devices. is there.

On the other hand, there is often no problem even if the received data is held at a value before the predetermined time.
SUMMARY OF THE INVENTION The present invention has been made in view of these points, and has as its object to provide a communication error processing method that makes the operator's work as unnecessary as possible at the time of communication error and at the time of error recovery.

[0005]

[Means for Solving the Problems] In order to achieve the above object, it is with the following configuration.

[0006] communication abnormality processing method for distributed process control system of the present invention, distributed in the case where communication error occurs in the digital process controller mutual continues suitable data processing data processing unit of the receiving device Is a communication error processing method for performing communication, when the receiving side process control device recognizes a communication error, holds the received data immediately before the communication error recovery time, the data processing unit based on this held data If the process control unit on the receiving side recognizes the abnormal recovery,
The stored data is compared with the new received data, and when the new received data differs from the stored data by a predetermined value or more, the data supplied to the data processing unit is changed at a predetermined change rate, and gradually , Which is close to the original received data.

[0007]

According to the present invention, the process control device on the receiving side is
When a communication error is recognized, the
The data processing unit keeps the data until the communication error recovery.
Continues data processing based on the data, and
If the process control unit of the
Compares the held data with the new received data and
When the communication data differs from the held data by a predetermined value or more
Changes the data supplied to the data processing unit to a predetermined value.
The rate is changed at a rate 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 changes significantly
Never do.

[0009] Note that how a recognizing abnormal restoration is not particularly limited, for example, when the operator sets the transmitting device in the automatic mode, on the basis of this fact, the abnormality restored at the receiving apparatus side May be recognized, so that a special operation for restoring the communication function is not required.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to embodiments. [Embodiment 1] FIG. 1 is a functional block diagram showing an embodiment of the first aspect of the present invention. This block diagram shows a state in which the CPU 1 of the transmitting device and the CPU 2 of the receiving device are connected via the communication bus 3. A flip-flop (FF) 4 that is reset at the time of a communication error and set at the time of error recovery,
Receiving the transmission data A _i to be transmitted through the communication bus 3 from 1, and the switching device (T) 5 to feed is provided this data processing unit (not shown).

[0011] A is the switching device 5 is supplied the output of the flip-flop 4, switching device 5, if the flip-flop 4 is set state, supplies the unchanged data processing unit to transmit data A _i from CPU 1, the flip If the loop 4 is in the reset state, the previous output data is held. In this embodiment, the flip-flop 4 and the switch 5 are represented by hardware, but are actually processed by a program.

The operation of the apparatus according to the first embodiment will be described below with reference to FIG. CPU2 according to a predetermined communication protocol, receiving the data A _i of CPU1 side, 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 the communication error. Specifically, for example, the data at the memory address for the flip-flop is set to 0.

[0013] switching device 5, when it is a part that the operation of supplying the data A _i which has received from the communication bus 3 into the data processing unit, for supplying the received data to the data processing unit,
Reference is made to the output of the flip-flop 4. Specifically, for example, when the data value of the memory address for the flip-flop is 0
Check whether or not. Now, assuming that a communication error has occurred, the switch 5 recognizes that a communication error has occurred from the data value of the flip-flop 4, and changes the same data (hereinafter referred to as hold data) as before. Supply to the processing unit.

Therefore, even if a communication error occurs, the CP
Automatic operation will be continued on the U2 side. still,
Since the hold data is supplied to the data processing unit, the operation is not the same as the normal operation, but there is a case where supplying the same data as before does not cause any problem. Works effectively. When the communication abnormality recovers, the flip-flop 4 is set in response 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 the normal operation state thereafter,
Supplied directly to the data processing unit data A _i received from the transmitting side CPU 1.

When the CPU 1 recovers to a normal state, the operator normally checks the fact and sets the system to the automatic mode. However, the CPU 2 checks the signal accompanying this setting for final normality. A signal may be received and the flip-flop 4 may be set. [Embodiment 2] FIG. 3 is a functional block diagram showing an embodiment of the second aspect of the present invention. The feature of this embodiment is that the switch 5
Next to the change rate setting device (RG) 6 and the deviation monitor (MO)
7 is provided. Also, the flip-flop 4 has C
It is configured to be set by an automatic signal transmitted from PU1.

The change rate setting unit 6 is a portion which operates initially a communication error is recovered only by comparing the error recovery original data values A _i and previous hold data values A _0, both the predetermined value In the case of a difference, the output value is changed at a constant rate. In this embodiment, the change rate setting device 6 and the deviation monitor 7 are realized by a program, 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 according to a predetermined communication protocol, receiving the data A _i of CPU1 side and supplies it to the data processing unit, when a communication error occurs, to reset the flip-flop 4 corresponds to this .

Then, the switch 5 is connected to the flip-flop 4
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, the mode of the automatic operation is continued by continuously supplying the hold data. Eventually, when the CPU 1 returns to the normal state, the operator confirms this and sets the system to the automatic mode. In the embodiment shown in FIG. 3, a set signal (automatic signal) is input to the flip-flop 4 in response to the operator's setting operation. Output _{i as} is.
That is, in this embodiment, the setting of the automatic mode (automatic signal) by the operator 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
Is supplied to the data processing section as it is, if the data A _i is greatly different from the level of the hold data A ₀ , the control amount for the control target may suddenly change. Therefore, the change rate setting unit 6 and the deviation monitor 7 appropriately control the data supplied to the data processing unit in the transition period after the recovery from the communication error as follows.

That is, the change rate setting unit 6 stores the hold data A ₀ and the data A _i at the time of communication error recovery (see FIG. 2).
Compared bets, if both data are different than the predetermined value, the output of the change rate setting device 6 from the level of the hold data A _0, a constant to a new level of the received data A _i changes varying by a factor (see T ₁ through T ₂ in Figure 2). On the other hand, the deviation monitor 7 monitors the input and output values of the change rate setter 6, and stops the operation of the change rate setter 6 when the output value of the change rate setter 6 matches the input value. Thereafter, the output of the switch 5 (this is nothing but reception 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 the number of CPUs is two has been described as an example, but the present invention does not limit the number of CPUs.

[0022]

As described above , according to the present invention, even if a communication error occurs, automatic operation can be performed thereafter, and the burden on the operator is reduced. In addition, the safety of the plant can be maintained as much as no operation by the operator is required. Further, at the time of communication error recovery, data transmission / reception can be resumed without any special inspection work such as checking signal data, and there is no possibility of sudden change at the time of error recovery.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one 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 apparatus of FIG. 3;

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

[Explanation of symbols]

 FF flip-flop T data switch

Claims (1)

(57) [Claims] If the communication error occurs 1. A distributed digital process control apparatus mutual a communication abnormality processing method for the data processing unit of the receiving device continues to perform appropriate data processing, reception If the side of the process control device recognizes the communication abnormality, holds the received data immediately before until communication error recovery, have row continues data processing based upon the data held by the data processing unit, the receiving process control When the device recognizes abnormal recovery
Comparing the held data with the new received data, and the new received data differs from the held data by a predetermined value or more.
Data to be supplied to the data processing unit,
Change at a constant rate of change, gradually approaching the original received data.
A communication error processing method for a distributed process control device, characterized in that: