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(4) Operation with starting ST
This section explains the operation of 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. Then PID constants are automatically
corrected. The following table lists the operations of the module with starting ST.
CH PID auto-correction status (b0 of RWr14 to RWr17) is turned 0 (OFF). In addition, CH Auto tuning status (RX20 to RX23) is
1
turned on.
2
Temperature is controlled using the PID constants set.
When a control response is poor, PID constants are calculated based on the response waveform and are set in the remote buffer
3
memory. CH PID auto-correction status (b0 of RWr14 to RWr17) is turned 1 (ON). When a control response is good, CH PID
auto-correction status (b0 of RWr14 to RWr17) remains 0 (OFF) and PID constants are not changed.
4
CH Auto tuning status (RX20 to RX23) is turned off.
Temperature process value (PV)
Set value (SV)
Control start
CH□ Auto tuning status
OFF
(RX20 to RX23)
CH□ PID auto-correction status
OFF
(b0 of RWr14 to RWr17)
Before change
PID constants
(a) Conditions for self-tuning
Starting ST is executed under the following conditions.
• The first change of the operating status from "stop" to "run" after power on
• The second and subsequent changes of the operating status from "stop" to "run" after power on (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 original (before set value change) temperature
process value (PV) has been stable for two minutes or longer)
If the starting ST is started when the temperature process value (PV) is not stable, incorrect PID constants may be
determined. Execute the starting ST after the temperature process value (PV) has been stable for two minutes or longer.
Operation with starting ST
Response measurement/evaluation
During self-tuning
ON
(Only when PID constants were changed)
(Only when the response failed)
Controlled by the temperature control module
CHAPTER 8 FUNCTIONS
Time
ON
After change
187
8
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Troubleshooting
