Mitsubishi Electric MELSEC iQ-R Series User Manual page 51

Operation with starting ST
This section describes the operation when the temperature control is started or the set value (SV) is changed (starting ST).
With starting ST, the module monitors the response waveform of the temperature process value (PV) of when the temperature
control is started or when the set value (SV) is changed, and automatically corrects PID constants.
The following describes the operations of the module with starting ST.
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.
The temperature is controlled using the set PID constants.
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)
Control start
'CH1 Auto tuning status'
(X4)
CH1 PID auto-correction status
(Un\G411, b0)
OFF
PID constants
■Conditions for execution
Starting ST is executed under the following conditions.
• When the mode is shifted from the setting mode to the operation mode ('Setting/operation mode command' (Y1) is turned
from OFF to ON) for the first time after the power is turned OFF and ON or after the CPU module is reset and the reset is
cleared
• When the mode is shifted from the setting mode to the operation mode for the second time or later after the power is turned
OFF and ON or after the CPU module is reset and the reset is cleared (only when the temperature process value (PV) has
been stable for two minutes or longer before the mode is shifted)
• When the set value (SV) is changed (only when the temperature process value (PV) before a change of the set value (SV)
has been stable for two minutes or longer)
When the starting ST is started when the temperature process value (PV) has not been stable, incorrect PID
constants may be calculated. Execute the starting ST after the temperature process value (PV) has been
stable for two minutes or longer.
Response measurement/evaluation
Self-tuning in execution
ON
OFF
(Only when PID constants were changed)
Before change
Executed by the temperature control module
ON
(Only for poor response)
Time
After change
1 FUNCTIONS
1.12 Self-tuning Function
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