YOKOGAWA UTAdvanced UP55A, User Manual

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6-27
IM 05P02C41-01EN
Monitoring and Control of Regular Operations
6
In Cascade control, perform Loop-2 auto-tuning in AUTO and RUN modes, then Loop-1
auto-tuning in Cascade and RUN modes.
Lamp Status
Status STOP lamp CAS lamp MAN lamp
During auto-tuning of Loop-2 Unlit Unlit Blinking
During auto-tuning of Loop-1 Unlit Lit Blinking
Description
Auto-tuning is a function with which the controller automatically measures the process
characteristics and sets PID constants, which are control-related parameters, to optimum
values for the setpoint. Auto-tuning temporarily executes ON/OFF control, calculates
appropriate PID constants from response data obtained, and sets these constants.
CAUTION
Do not perform auto-tuning for the following processes.
Tune PID manually.
● Processes with fast response such as flow rate control and pressure control.
● Processes which do not allow the output to be turned on and off even
temporarily.
● Processes which prohibit output changes at control valves (or other actuators).
● Processes in which product quality can be adversely affected if PV values
fluctuate beyond their allowable ranges.
AT = Started
ON
OFF
Temperature
SP
Control
output
Time
ON/OFF control
PID control using PID
constants calculated from
the AT results
Auto-tuning in progress
MAN lamp blinkng
There is a hysteresis of 0.25% of the input range above and below SP.
When SP bias in auto-tuning is set
AT = Started
ON
OFF
Temperature
SP+AT.BS
SP
Control
output
Time
ON/OFF control
SP bias in auto-tuning
(negative setpoint)
PID control using PID
constants calculated from
the AT results
Auto-tuning in progress
MAN lamp blinkng
There is a hysteresis of 0.25% of the input range above and below SP.
6.2 Performing and Canceling Auto-tuning