4.2 Control Mode Selection Function - Mitsubishi Electric MELSEC iQ-F FX5 User Manual

Items
Error history function
FX3 allocation mode function
4.2
Control Mode Selection Function
This function selects the I/Os (external or internal) to be used as the control type (standard PID control for heating and cooling
PID control) for each control group.
The control groups are divided as described below.
• Control group 1: CH1 and CH2
• Control group 2: CH3 and CH4
Standard PID control, heating and cooling PID control
There are two types of control modes in the temperature control module: Standard PID control and heating-cooling PID
control.
■Standard PID control
This control method attempts to acquire stable control results by setting the constants for P (proportional band) I (integral
time) and D (derivative time).
"Response to noise" worsens for this PID control if the PID constants are set to improve "Response to settings". Further,
"Response to settings" worsens if the PID constants are set to improve "Response to noise".
The temperature control module can be used to select "Fast", "Normal", and "Slow" using the control response parameters for
the shape of the "Response to settings" with the PID constants to improve "Response to noise" unchanged.
■Heating/cooling PID control
Heating and cooling PID controls are the control methods that operate the outputs for both the heating and cooling control
systems.
In heating, the manipulated value (MV) operation decreases (reverse operation) according to increases in the process value
(PV), and in cooling, the manipulated value (MV) operation increased (normal operation) according to increases in the
process value (PV).
Set cooling and heating PID constants individually for proportional band (P) cooling and heating. Integral time (I) and
derivative time (D) are common set values for both heating and cooling.
Consequently, the temperature control module implements calculations using the four PID constants of heating proportional
band, cooling proportional band, integral time, and derivative time.
Further, it is possible to establish dead bands, and implement overlap and outputs, using the heating and cooling control
switching points.
4 FUNCTION
24

4.2 Control Mode Selection Function

Description
This function stores a maximum of 16 errors and alarms
that occurred in the temperature control module to buffer
memory as a history.
The temperature control module buffer memory
addresses can be arranged in the same way as for
FX3U-4LC.
Usability
Standard PID Heating/cooling
control PID control
 
 
Reference
Page 65
Page 68