JPH10340119A - Program control hunting prevention device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a program control hunting prevention device having high reliability. SOLUTION: This device decides the continuation of DI (digital) start signals via a timer integration decision circuit and a target value arrival decision circuit when a set timer starting circuit starts and the DI start signals are continuous for a prescribed time or longer. Then the device adds its arithmetic result to an operation output arithmetic processing circuit 14 with no change of the SV(set value) and even in a normal PID (proportion, integration, differentiation) control state to control a process signal. Thus, the device operability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a PID control SV.
The present invention relates to a program control hunting prevention device for preventing hunting of control for performing a target value program by internal calculation without using a value.

[0002]

2. Description of the Related Art Conventionally, a program start signal
The control is performed by controlling the operation output (MV value) so as to be set to the target value by a process signal and an internal calculation without using the SV value of the PID control, and performing the program control in a fixed section.

At this time, when the process signal rarely performs a hunting operation, it is desired to execute the program control for a certain section. However, the hunting causes an irregular operation such that the program repeats "start" and "end" several times. ing.

[0004]

However, to prevent the hunting of the process signal, various methods such as a digital filter and a hiss width can be considered. However, when the setting range is narrow, it is not adopted, and there is a case where the program control cannot be executed. is there.

It is an object of the present invention to provide a program control hunting prevention device capable of performing arithmetic processing with a simple configuration.

[0006]

SUMMARY OF THE INVENTION A program control hunting prevention apparatus according to the present invention is a circuit for changing a control target value according to a preset set value and performing program control. Even if the process signal is hunting, a function to determine whether or not the target value is set within a predetermined period of time from when the set value is entered is provided. Features.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a program control hunting prevention device according to the present invention will be described. FIG. 1 is a functional flow block diagram showing that the determination circuit has a function of achieving a target value even when a process signal hunts.

Now, a DI (digital) start signal is input to the set timer start circuit 2 via the DI switch ON determination circuit 1, the set timer start circuit 2 is started, and the DI start signal is kept at a predetermined time or more. , The timer integration determination circuit 3 and the target value arrival determination circuit 4 determine the continuation of the DI start signal, and during normal PID (proportional / integral / differential) control,
Operation output arithmetic processing circuit 14 without changing SV (setting) value
To control the process signal.

In addition, by taking into account the operation output calculated by the set value PV judgment circuit 5 and the target set value judgment circuit 6, the condition satisfaction judgment circuit 12 is operated, and the program control execution circuit 13 is further executed. The signal can move towards the target value.

When the process signal enters the program control execution range by the set value PV judgment circuit 5 and the target set value judgment circuit 6, the set time duration judgment circuit 7
, The signal inversion circuit 8 inverts the signal, the signal change determination circuit 9 determines the signal change, and the hunting prevention signal output circuit 11 is output by the output signal circuit 10 due to the signal change. The operation is performed to generate a hunting prevention signal, and the program control execution circuit 13 is executed.

In the case where the value has dropped too much, the calculation result is output to the operation terminal as the target value of the target set value judging circuit 6, and the program returns to the control within the normal set value, thereby enabling stable program control.

FIG. 2 is an explanatory diagram showing the operation of FIG. 1. The reset signal 22 is a signal for judging the start signal (D1) 21.
Operation starts at the rise of. And process signal 2
When the value 5 exceeds the set value 24, the hunting prevention signal 27
Rise, and the program control execution 28 operates. In addition, 26 is a signal by a process.

As described above, according to this embodiment, even if the hunting occurs in the process signal, the execution of the program control is not repeated many times by the set value range, the set time duration determination and the arithmetic processing, and the process signal is stabilized. Control within the set target value can be made possible.

[0014]

According to the present invention, the operability of the program control hunting prevention device can be improved.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a program control hunting prevention device according to an embodiment of the present invention.

FIG. 2 is an operation explanatory view of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Judgment circuit 2 Setting timer start circuit 3 Timer integration judgment circuit 4 Target value arrival judgment circuit 5 Set value PV judgment circuit 6 Target set value judgment circuit 7 Set time duration judgment circuit 8 Signal inversion circuit 9 Signal change judgment circuit 10 Output signal circuit 11 Hunting prevention signal output circuit 12 Condition satisfaction determination circuit 13 Program control execution circuit 14 Operation output operation processing circuit

Claims (1)

[Claims] 1. A program control circuit for changing a control target value according to a preset set value and performing a program control, comprising an arithmetic circuit for judging the end of the program control when the set value is reached by a process signal. Hunting prevention device.