Chapter 11 Process Control Instructions; Overview; Basic Loop Types - Mitsubishi Electric MELSEC iQ-R Series Programming Manual

11
PROCESS CONTROL INSTRUCTIONS
When a process control program is created, using process control function blocks is recommended
Process control function blocks have features as follows.
• A process control program can be easily created by placing and connecting FB elements.
• Since the initial value of the function block can be set in the "FB Property" window of the engineering tool,
the program for the initial value setting is not required.
• An operation constant can be input to a label indicating a tag name without being conscious of address of a
device.
• The operating status of a tag FB can be checked and controlled by accessing the tag data from the
faceplate of an engineering tool.
For details on the process control function blocks, refer to the following.
 MELSEC iQ-R Programming Manual (Process Control Function Blocks)
11.1

Overview

This section describes the loop type that can be configured by process control instructions, data configurations of the
instructions, instruction execution methods, and precautions.

Basic loop types

The following table summarizes basic loop types configured by combinations of process control instructions.
Loop type Configuration
Two-degree-of-freedom
SET
PID control (S2PID)
INPUT
SET
INPUT
PID control (SPID)
SET
INPUT
SET
INPUT
PIDP control (SPIDP)
SET
INPUT
Sample PI control (SSPI)
SET
INPUT
I-PD control (SIPD)
SET
INPUT
SV
PV MV
S.IN S.PHPL S.2PID S.OUT1
SV
PV
MV
S.IN S.PHPL S.2PID S.DUTY
SV
PV
MV
S.IN S.PHPL S.PID S.OUT1
SV
PV MV
S.IN S.PHPL S.PID S.DUTY
SV
PV
MV
S.IN S.PHPL S.PIDP
SV
PV
MV
S.IN S.PHPL S.SPI S.OUT1
SV
PV
MV
S.IN S.PHPL S.IPD S.OUT1
Application
Used for general PID control (two degrees of freedom). (Speed
type)
PID operation is performed every control cycle.
OUTPUT
OUTPUT
Used for general PID control. (Speed type)
PID operation is performed every control cycle.
OUTPUT
OUTPUT
Used for general PID control. (Position type)
PID operation is performed every control cycle.
OUTPUT
Used for processes which involve much dead time.
PI control is executed only for the control execution time every
control cycle, and later output is held constant.
OUTPUT
Used to make a slow response so as not to give a shock to the
operation terminal and process when the set value is changed.
OUTPUT
11 PROCESS CONTROL INSTRUCTIONS
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11.1 Overview