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127
Operation selection function
2
FUNCTIONS
(4) I/O signals
• Enter the set point across inverter terminals 2-5 or in Pr. 93 and enter the measured
value signal across inverter terminals 4-5.
• To exercise PID control, turn on the X14 signal. When this signal is off, PID control is
not exercised.
(5) Parameter setting
Signal Terminal Used Function Description
Input
X14
Depending on
Pr. 60 to Pr. 63
PID control
selection
Turn on X14 to exercise PID control.
2 2 Set point input Enter the set point for PID control.
44
Measured value
input
Enter the 4 to 20mADC measured value
signal from the detector.
Output
FUP
Depending on
Pr. 64, Pr. 65
Upper limit output
Output to indicate that the measured value
signal exceeded the upper limit value.
FDN Lower limit output
Output to indicate that the measured value
signal exceeded the lower limit value.
RL
Forward (reverse)
rotation direction
output
"Hi" is output to indicate that the output
indication of the parameter unit is forward
rotation (FWD) or "Low" to indicate that it is
reverse rotation (REV) or stop (STOP).
Item Entry Description
Set point
Across
terminals 2-5
Set 0V as 0% and 5V as 100%.
When "0" is set in Pr. 73 (5V
selected for terminal 2).
Set 0V as 0% and 10V as 100%.
When "1" is set in Pr. 73 (10V
selected for terminal 2).
Pr. 93 Set the set point (%) in Pr. 93.
Measured
value
Across
terminals 4-5
4mA is equivalent to 0% and 20mA to 100%.
Parameter
Number
Name Setting Description
88
PID action
selection
20 For heating, pressure control, etc. PID reverse action
21 For cooling, etc. PID forward action
89
PID
proportional
band
0.1 to 999%
If the proportional band is narrow (parameter setting is
small), the manipulated variable varies greatly with a slight
change of the measured value. Hence, as the proportional
band narrows, the response sensitivity (gain) improves but
the stability deteriorates, e.g. hunting occurs.
Gain K = 1/proportional band
- - - No proportional control
90
PID integral
time
0.1 to 999s
Time required for the integral (I) action to provide the
same manipulated variable as that for the proportional
(P) action. As the integral time decreases, the set point
is reached earlier but hunting occurs more easily.
- - - No integral control.