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LADDER LOGIC • FX5U / GX WORKS3

How do I create a motor start/stop seal-in circuit in FX5U ladder?

Place the healthy stop and overload conditions in series, then place the start contact in parallel with the output holding contact before the motor output coil.

Practical explanation

This gives stop priority when the stop/healthy condition opens.

The PLC logic does not replace hardwired safety and overload protection.

Check in this order

  1. 1Confirm whether stop and overload inputs are wired normally closed.
  2. 2Add all machine permissives.
  3. 3Test loss and restoration of PLC power.

Ladder instruction example

LD X1
AND X2
MPS
AND X0
MPP
OR Y0
OUT Y0

Example only—allocate devices and interlocks for your own project.

Devices and registers

X0: start pushbutton
X1: stop circuit healthy
X2: overload healthy
Y0: motor contactor command

Safety: Use certified hardwired safety circuits and a correctly rated motor protection device.

Last reviewed: 2 October 2026

Official source: MELSEC iQ-F FX5 Programming/Application manuals

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