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10 PID CONTROL FUNCTION
10.6 Details of Parameters
Operation setting (s3)+1
Forward operation/backward operation
Set the PID control direction (forward or backward).
• During auto-tuning for the limit cycle method
It is necessary to set the PID control direction (forward or backward) for auto-tuning.
• During auto-tuning for the step response method
The PID control direction (forward or backward) is not required, as the direction is automatically set when auto-tuning is
complete.
• Relationship between the forward/backward operation and the output (MV), measured value (PV) and target value (SV)
The relationship is as follows.
Operation setting (s3)+1: b0 Operation
Forward
operation
(b0=OFF)
As the measured value (PV) becomes larger than the target value
(SV), the output (MV) increases.
For example, cooling is a forward operation.
Backward
operation
(b0=ON)
As the measured value (PV) becomes smaller than the target value
(SV), the output (MV) increases.
For example, heating is a backward operation.
Temperature
Measured value (PV)
Time
Target value (SV)
Temperature
Measured value (PV)
Time
Target value (SV)
Measured value (PV)
Output value (MV)
Target value (SV)
Backward
operation
Forward
operation
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