Control Mode Switch Function - Mitsubishi Electric MELSEC FX Series User Manual

FX -4LC User's Manual
3U
6.2

Control Mode Switch Function

The control mode switch function sets the control type (PID control, two-position control, manual control,
cascade control or heating/cooling control) and used input/output (external or internal) for each control group.
Make sure to set the control mode before performing control.
Up to 4 loops are available for each control type. However, only up to 2 loops are available for cascade
control.
Control groups are classified into the group 1 (CH1 and CH2) and group 2 (CH3 and CH4).
Control mode
Control mode
0
1
2
3
4
5
6
7
• When internal input is selected
The 4LC performs control using measured values detected through inputs built into the 4LC.
• When external input is selected
The 4LC performs control using values stored in external input value buffer memories (BFM#25 to
BFM#28) without using inputs built into the 4LC.
• When internal output is selected
The 4LC performs control using transistor outputs built into the 4LC. However, in heating/cooling PID
control, the control output of CH2 and CH4 should use an external output.
• When external output is selected
The 4LC performs control using values stored in external output value monitor/heating external output
value monitor buffer memories (BFM#32 to BFM#35) and cooling external output value monitor buffer
memories (BFM#36 to BFM#39) without using transistor outputs built into the 4LC. The transistor output
built into the 4LC is controllable when transistor output selections 1 and 2 are chosen. Additionally the
outputs can also be used as alarm outputs.
34
Control type Input
Internal
PID control
External
Two-position control
Manual control
Internal
Cascade control
External
Internal
Heating/cooling PID
External
control
Internal
Two-position control
External
→ For details on the external input value, refer to Subsection 8.2.8.
→ For details on the external output value, refer to Subsection 8.2.11 or 8.2.12.
→ For details on the transistor output selection, refer to Subsection 8.2.50.
6.2 Control Mode Switch Function
Output
Internal
External
Internal
External
6 Introduction of Functions