Determining Pid Constants(At, St, Manual Setup); Determining Pid Constants (At, St, Manual Setup); At (Auto-Tuning) - Omron E5*C Series User Manual

4 Basic Operation
4-9 Determining PID Constants
(AT, ST, Manual Setup)
4-9-1

AT (Auto-tuning)

at
 AT Operations
AT is started when either at-2 (100% AT) or at-1 (40% AT) is specified for the AT Execute/Cancel
parameter.
The TUNE indicator will light during execution.
Only the Communications Writing, RUN/STOP, AT Execution/Cancel, and Program Start parameters
can be changed during AT execution. Other parameters cannot be changed.
AT Calculated Gain
The AT Calculated Gain parameter sets the gain for when PID values are calculated using AT. When
emphasizing response, decrease the set value. When emphasizing stability, increase the set value.
AT Hysteresis
The AT Hysteresis parameter sets the hysteresis when switching ON and OFF for the limit cycle
operation during auto-tuning.
4 - 24
• When AT is executed, the optimum PID constants for the set point at that time
are set automatically. A method (called the limit cycle method) for forcibly
changing the manipulated variable and finding the characteristics of the
control object is employed.
• Either 40% AT or 100% AT can be selected depending on the width of MV
variation in the limit cycle. In the AT Execute/Cancel parameter, specify at-2
(100% AT) or at-1 (40% AT). To cancel AT, specify off (AT cancel).
• Only 100% autotuning is supported for heating and cooling control or floating
position-proportional control.
• If the Heating/Cooling Tuning Method parameter is set to any value other than
0 (same as heating control), the PID constants are set automatically for both
heating control and cooling control.
• AT cannot be executed when control has stopped or during ON/OFF control.
• The results of autotuning are saved in the following parameters in the
Adjustment Level: Proportional Band (P), Integral Time (I), Derivative Time
(D), Proportional Band (Cooling) (C-P), Integral Time (Cooling) (C-I), and
Derivative Time (Cooling) (C-D).
Adjustment Level
p
Proportional
Band
8.0
i
Integral
Time
233
d
Derivative
Time
40
000
000
c-p
Proportional
Band (Cooling)
8.0
c-i
Integral Time
(Cooling)
233
c-d
Derivative Time
(Cooling)
40
E5@C Digital Temperature Controllers User's Manual (H174)