L-14
3 Parameter
FX
3G
/FX
3U
/FX
3UC
PLC User's Manual - Analog Control Edition
PID Instruction (FNC 88)
3.2 Details of Parameters
Example 1: PI operation in heating (backward operation)
Example 2: Proportional operation (P operation) in cooling (forward operation)
Important point
The integral operation changes the output so that the continuously generated deviation is eliminated.
As a result, the remaining deviation generated in the proportional operation can be eliminated.
Time
Target
value (SV)
Measured value in proportional operation
Temperature
T
I3
0 < T
I3
< T
I2
< T
I1
Measured value in PI operation
T
I2
T
I1
Time
Output in proportional operation
Output (MV)
T
I3
Output in PI operation
T
I2
T
I1
0 < T
I3
< T
I2
< T
I1
Integral time (T
I
)
Integral time (T
I
)
Time
Target
value(SV)
Measured value in proportional operation
TI3
Measured value in PI operation
TI2
TI1
0 < TI3 < TI2 < TI1
Time
Output in proportional operation
TI3
TI2
TI1
Output in PI operation
0 < TI3 < TI2 < TI1
Integral time (TI)
Integral time (TI)
Temperature
Output (MV)
Time
Deviation(EV)
Deviation
Time
Output of
"proportional operation + integral operation"
Output of proportional operation
Proportional gain (K
P
) × Deviation (E)
Output of integral operation
Integral time (T
I
)
Output
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