Outline Of Function - Mitsubishi MELSEC-F FX3U Series User Manual

FX /FX Series PLC User's Manual - Analog Control Edition
3U 3UC
PID Instruction (FNC 88)
1. Outline
This chapter describes the outline of PID instruction (FNC88) for the FX
1.1

Outline of function

PID instruction orders the system to calculate the output (MV) value from the measurement (PV) value so that
combining the P (proportional) action, I (integral) action, and D (derivative) action can obtain the target (SV)
value. See diagram below.
1) Alarm output function
The alarm input can be set to ON for the input (measured value) variation or output (value) variation.
2) Setting the upper limit and lower limit of the output value
The upper limit and lower limit can be set for the output value.
3) Auto tuning function
The proportional gain (KP), integral time (TI) and differential time (TD) can be set automatically.
The limit cycle method or step response method can be selected.
4) Operation method of the PID instruction
PID speed type operation and measured value differential type operation are executed.
FX
Target value
(SV)
/FX
Series PLC
3U 3UC
PID Instruction
/FX
3U 3UC
Measurement value (PV)
Controlled
Output value (MV)
1 Outline
1.1 Outline of function
Series PLC.
object
G-3
A
B
C
D
E
F
G