<Toc>
<6. Parameters>
6-9
IM 05E01D02-41E
1st Edition : May 31,2000-00
■
Auto-tuning
Auto-tuning is a function with which the controller automatically measures the process
characteristics to automatically set the optimum PID constants. This function does not work
when the controller is performing on-off control. The UP350 employs the “Limit Cycle
Method.” As shown in the figure below, the controller temporarily changes its control output
in a step-waveform manner. Then, it calculates the optimum proportional band (P), integral
time (I) and derivative time (D) from the resulting response to set them in their respective
parameters. If the Output High Limit (OH) and Output Low Limit (OL) parameters are
already configured, the control output turns on and off only between the output’s high and
low limits during auto-tuning.
PV input value
Control output
Interval of auto-tuning
Auto-tuning is
complete when the
3rd peak arrives.
PID control based on
PID constants determined
by auto-tuning
On
Off
On
Setpoint
Time
Start of
auto-tuning
On
Off
●
When One Group of PID Constants is Used (factory-set default)
Setting of
AT Parameter
Auto-tuned Setpoint
Remarks
OFF
-
Auto-tuning is turned off (disabled).
1
The setpoints when auto-tuning is started
Determines the values of 1.P, 1.I and 1.D parameters by auto-tuning.
●
When Two Groups of PID Constants are Used (See “
■
PID Switching
(Zone PID)” below)
Auto-tuned Setpoint
Remarks
OFF
Auto-tuning is turned off (disabled).
The setpoints when auto-tuning is started
The setpoints when auto-tuning is started
-
1
Determines the values of 1.P, 1.I and 1.D parameters by auto-tuning.
2
Determines the values of 2.P, 2.I and 2.D parameters by auto-tuning.
AUTO
Median value of each zone width
Determines the values of all PID parameters in use by auto-tuning.
Setting of
AT Parameter
●
When Three Groups of PID Constants are Used (See “
■
PID Switching
(Zone PID)” below)
Setting of
AT Parameter
Auto-tuned Setpoint
Remarks
OFF
Auto-tuning is turned off (disabled).
The setpoints when auto-tuning is started
The setpoints when auto-tuning is started
The setpoints when auto-tuning is started
Determines the values of all PID parameters in use by auto-tuning.
-
1
Determines the values of 1.P, 1.I and 1.D parameters by auto-tuning.
2
Determines the values of 2.P, 2.I and 2.D parameters by auto-tuning.
3
Determines the values of 3.P, 3.I and 3.D parameters by auto-tuning.
AUTO
Median value of each zone width
Summary of Contents for UP350
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