Mitsubishi Q Mode, Руководство по программированию

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MELSEC-Q/QnA
1. GENERAL DESCRIPTION
1.1 PID Processing Method
This section describes the processing method for PID control using PID control
instructions. (For details on PID operations, see Chapter 4.)
Execute PID control with PID control instructions by loading an A/D converter module
and a D/A converter module, as shown in Figure 1.1.
CPU module
Set value
PID control instructions
PID operation
PV
SV
D/A conversion
module
A/D conversion
module
Sensor
Manual MV
Manual/automatic
changeover
Automatic
MV
MV
PV
SV: Set Value
PV: Process Value
MV: Manipulated Value
Controlled
system
Figure 1.1 Overview of PID Control Processing
In the PID control processing method, as shown in Figure 1.1, the PID operation is
executed using the set value (SV) and the process value (PV) read from the A/D
converter module, and the manipulated value (MV) is then calculated.
The calculated MV (manipulated value) is output to the D/A converter module.
When a PID operation instruction* is executed in a sequence program, the sampling
cycle is measured and a PID operation is performed.
PID operation in accordance with the PID operation instruction is executed in preset
sampling cycles.
Sequence program
Step 0
PID operation
instruction
execution
Sampling cycle
Step 0 Step 0
Step 0 Step 0
Measurement of
sampling cycle
END END END END
Measurement of
sampling cycle Measurement of
sampling cycle
Sampling cycle
Measurement of
sampling cycle
PID operation Measurement of
sampling cycle
PID operation
PID operation
instruction
execution PID operation
instruction
execution PID operation
instruction
execution PID operation
instruction
execution
Figure 1. 2 Operation when PID Operation Instruction Executed
REMARK
*:
There are the following PID operation instructions.
S.PIDCONT (incomplete derivative)
PIDCONT (complete derivative)