(A) Application parameters
PARAMETERS
515
5
GROUP
A
Calibration of PID display bias and gain(C42 (Pr.934) to C45 (Pr.935))
• When both C42 (Pr.934) and C44 (Pr.935) "9999", the bias and gain values for the set point, measured value and
deviation in PID control can be calibrated.
• "Bias"/"gain" function can adjust the relation between PID displayed coefficient and measured value input signal that is
externally input.
Examples of these measured value input signals are 0 to 5 VDC, 0 to 10 VDC, or 4 to 2 mADC.
• Set the value that is displayed when the PID measured value (control amount) is 0% to C42
(Pr.934) and the value that is
displayed when the PID measured value (control amount) is 100% to C44 (Pr.935).
• When both of C42
(Pr.934) and C44 (Pr.935) "9999” and Pr.133 is set as the set point, the setting of C42 (Pr.934) is
treated as 0%, and C44
(Pr.935) as 100%.
• There are three methods to adjust the PID display bias/gain.
(a) Method to adjust any point by application of a current (voltage) to the measured value input terminal
(b) Method to adjust any point without application of a current (voltage) to the measured value input terminal
(c) Method to adjust only the display coefficient without adjustment of current (voltage)
(Refer to page 415 for details on (a) to (c), and make the necessary adjustments by considering C7
(Pr.905) as C45 (Pr.935)
and Pr.126 as C44
(Pr.935).
NOTE
• Always calibrate the input after changing the voltage/current input specification with Pr.73 and Pr.267, and the voltage/
current input selection switch.
• Take caution when the following condition is satisfied because the inverter recognizes the deviation value as negative
(positive) value even though a positive (negative) deviation is given: Pr.934 (PID bias coefficient) Pr.935 (PID gain
coefficient)
To perform a reverse action, set Pr.128 PID action selection to forward action. Alternatively, to perform a forward action,
set Pr.128 to reverse action.
(Example) Set the following: Pr.934="500", 20% (4 mA is
applied), Pr.935="100", 100% (20 mA is applied).
When the set point=400 and the measured value=360, the
deviation is +40 (>0), but the inverter recognizes the
deviation as -10% (<0). Because of this, operation amount
does not increase in the reverse operation setting.
The operation amount increases when the forward operation
is set.
To perform PID output shutoff release at deviation of +40 or
higher, set Pr.577="960".
Pr.934 Pr.935 (normal setting) Pr.934 Pr.935
Reverse action Reverse action setting to Pr.128 Reverse action Forward action setting to Pr.128
Forward action Forward action setting to Pr.128 Forward action Reverse action setting to Pr.128
PID output shutoff release level Pr.577 -1000 PID output shutoff release level 1000 -Pr.577
100
0
0
0
0
Frequency setting signal
100%
20mA
5V
10V
C45 (Pr.935)
Initial value
Bias
C42 (Pr.934)
Gain
C44 (Pr.935)
20
4
1
2
C43 (Pr.934)
Coefficient
0
100%
500
20%
100
400
360
(0%) (25%) (35%) (100%)
Set point
Measured value
Deviation +40
Deviation -10%
∗ ( ) indicates the deviation value
which the inverter can recognize
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