Omron RX User Manual page 139

PID Output Limit Function
•This function limits PID output within a variable range relative to the target value.
•To use this function, set PID output limit function A078. The output frequency will be limited within
a range of "target value ± (A078)", with the maximum frequency defined as 100%.
•With A078 set to 0.0, this function is disabled.
PID output (%)
PID target
value
PID Reverse Output
•When a PID operation result is a negative value under normal PID control, the frequency reference
to the Inverter is limited at 0 Hz. However, if PID selection A071 is set to "02" (reverse output
enabled), reverse output can be provided for the Inverter when the PID operation result is a negative
value.
•When A071 = 02, the above-mentioned PID variable range limit function and the PID output stop
function are disabled.
PID Gain Adjustment
•If a stable response cannot be obtained in PID function operation, adjust each gain as follows
according to the situation.
•Feedback value variation is slow when the target value is changed.
•The feedback value changes fast but isn't stable.
•The target and feedback values wouldn't match smoothly.
•The feedback value fluctuates unstably.
•Response is slow even with P gain raised.
•With P gain raised, the feedback value vibrates and isn't stable.
Excessive Deviation/Output
•You can set PID deviation excessive level C044 during PID control. With this function allocated,
the multi-function output terminal is turned on when the PID deviation
C044.
•C044 can be set from 0 to 100. The setting corresponds to the range of 0 to the maximum target
value.
•Allocate 04 (OD) to any of multi-function output terminals C021 to C025 or relay output terminal
C026.
Feedback Comparison Signal
•If a PID feedback value is out of the specified range, it can be output to a multi-function output
terminal.
•Allocate 31 (FBV) to any of multi-function output terminals C021 to C025 or relay output terminal
C026.
4-2 Function Mode
PID output range
PID variable range (A078)
PID variable range (A078)
Time (s)
→ Raise P gain A072.
→ Lower P gain A072.
→ Lower I gain A073.
→ Raise I gain A073.
→ Raise D gain A074.
→ Lower D gain A074.
ε
reaches the set level in
4
4-34