# Mitsubishi Electric FR-A820-00046 (0.4K) Instruction Manual Page 586

Fr-a800 series.

• "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. (The
terminals used for measured value input can be selected at Pr.128, Pr.609, Pr.610.)
• 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.
Method to adjust any point by application of a current (voltage) to the measured value input terminal
Method to adjust any point without application of a current (voltage) to the measured value input terminal
Method to adjust only the display coefficient without adjustment of current (voltage)
(Refer to
page 482
for details, 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 a 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. In this case, the PID output shutoff release level is (1000 - Pr.577).
Pr.934 < Pr.935 (normal setting)
Reverse action
Forward action
PID output shutoff release level
(Example) Set the following: Pr.934 = "500" or 20% (4 mA is applied), Pr.935 = "100" or 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".
100
Bias
C42 (Pr.934)
0
20
0
4
Frequency setting signal
0
1
0
2
C43 (Pr.934)
Reverse action setting to Pr.128
Forward action setting to Pr.128
Pr.577 - 1000
Initial value
Gain
C44 (Pr.935)
100%
20mA
5V
10V
C45 (Pr.935)
Pr.934 ≥ Pr.935
Reverse action
Forward action
PID output shutoff release level
Forward action setting to Pr.128
Reverse action setting to Pr.128
1000 - Pr.577
5. PARAMETERS
5.14 (A) Application parameters
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