Omron RX - Page 139

4-34
4-2 Function Mode
4
Functions
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 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.  Raise P gain A072.
•The feedback value changes fast but isn't stable.  Lower P gain A072.
•The target and feedback values wouldn't match smoothly.  Lower I gain A073.
•The feedback value fluctuates unstably.  Raise I gain A073.
•Response is slow even with P gain raised.  Raise D gain A074.
•With P gain raised, the feedback value vibrates and isn't stable.  Lower D gain A074.
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
 reaches the set level in
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.
PID output (%)
PID target
value
PID output range
PID variable range (A078)
PID variable range (A078)
Time (s)