Process Control By Using Process Control Instructions - Mitsubishi Electric MELSEC iQ-R Series User Manual

Process control by using process control instructions

This function performs various types of process control by using process control instructions that support loop control, such as
two-degree-of-freedom PID control, sample PI, and auto tuning, in combination.
Since each processing of the PID control is subdivided and multiple process control instructions are used in combination, this
function performs more accurate and sensitive control than the PID control function.
*1
Set value
SV
*2
PV
*1 SV: Set value
*2 PV: Process value
*3 MV: Manipulated value
Process control instructions have the following features:
• Increased efficiency of system adjustment: Multiple process control instructions are combined to perform PID control, and
operation can be checked for each instruction individually.
• Application to a wide range of control: Another process control instruction can be added to the existing control loop, which
consists of multiple process control instructions, as an option.
• Configuration of safety system: Alarms are automatically detected in the system.
• Auto tuning: The auto tuning instruction automatically calculates PID constants that are most suitable for the control
system.
• When the process control function is used, the process control by the process control function block is
recommended. For the process control function block, refer to the following.
 MELSEC iQ-R Programming Manual (Process Control Function Blocks/Instructions)
• For the specifications of process control instructions, basic loop types, and programming details, refer to the
following.
 MELSEC iQ-R Programming Manual (Process Control Function Blocks/Instructions)
Process control instructions
are used.
Inside the CPU module
Automatic MV
PID operation
Each processing of the PID control is subdivided (micro-block).
Manual MV
*3
MV
D/A converter module
A/D converter module
21 PID CONTROL/PROCESS CONTROL FUNCTION
Controlled
system
Sensor
21.2 Process Control Function
21
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