Mitsubishi Electric MELSEC iQ-R Series User Manual page 52

Operation with vibration ST
This section describes the operation of when a control response is oscillatory (vibration ST).
With vibration ST, PID constants are automatically corrected to settle a vibration when a control response becomes oscillatory
due to some causes such as the change of the characteristics of a controlled object and operation conditions.
The following describes the operations of the module with vibration ST. (The listed operations are under the state where the
temperature is being controlled with the set PID constants.)
1.
CH1 PID auto-correction status (Un\G411, b0) is turned OFF. 'CH1 Auto tuning status' (X4) turns ON. ( Page 237
CH1 Self-tuning flag, Page 159 Auto tuning status)
2.
PID constants are calculated based on a response waveform.
3.
When a control response is poor, PID constants are calculated based on the response waveform and are set in the buffer
memory. CH1 PID auto-correction status (Un\G411, b0) is turned ON. When a control response is good, CH1 PID
autocorrection status (Un\G411, b0) keeps OFF and the PID constants are not changed. ( Page 237 CH1 Self-tuning
flag)
4.
'CH1 Auto tuning status' (X4) turns OFF. ( Page 159 Auto tuning status)
Temperature process value (PV)
Set value (SV)
'CH1 Auto tuning status'
(X4)
CH1 PID auto-correction
status (Un\G411, b0)
PID constants
■Conditions for execution
When the temperature process value (PV) is out of the range considered as stable, vibration ST is executed.
■Precautions
When vibration ST is executed to the following controlled objects, inappropriate PID constants may be calculated.
• Controlled objects where a disturbance periodically occurs
• Controlled objects with strong mutual interference
1 FUNCTIONS
50
1.12 Self-tuning Function
Oscillation detected
ON
OFF
Depends on previous
execution result OFF
Executed by the temperature control module
PID constants calculated
Response measurement
Self-tuning in execution
Before change
Time
ON
After change