20
5.7
Auto-tuning Introduction
Information.
• On demand user-activated tuning.
• Two types of auto-tuning – initial
'Start-up'
and when close to
Set Point
.
• Tuning for P, P.I. or P.I.D. control can be selected.
• Tuning for
1
/
4
wave damped or minimum overshoot can be selected.
• Automatic entry of calculated control terms – unless an auto-tune error occurs.
• Error and Caution messages – indicate reason for tuning problems.
Self-tune High Limit
Self-tune Low Limit
Hysteresis
Band
Hysteresis
Value
Output Step
Values at
Start of
Execution
Controller
Output
Time
Signal Noise
Set Point
PV
Output
Time
Output Step
Size
Time
Calculated Trip
Point
Information. The noise level of the
process is monitored and then a step is applied
to the control output value. The response of the
process is recorded and these results are used
to calculate the control terms.
Fig. 5.6 ‘Start-up’ Auto-tuning
Information. 'At Set Point' auto-tuning
automatically calculates the P.I.D. terms based
on the process reaction during an auto-tuning
cycle. The controller output is manipulated to give
six process oscillations which are used to
determine the tuning parameters.
Fig. 5.7 ‘At Set Point’ Auto-tuning
…5 CONTROL OPERATION
Summary of Contents for COMMANDER 1900 Series
Page 42: ...40 NOTES ...
