External Fault (LI/Bit)

What does EPF1 mean?

An external fault detected from a logic input (LI) or a local link. This indicates that an external safety device, sensor, or interlock has triggered a fault condition, causing the drive to stop. The specific cause depends on the connected device and its state.

• Open circuit in the wiring connecting an external safety device (e.g., E-stop, limit switch) to the drive's logic input (e.g., LI3).
• Mechanical failure of an external sensor or interlock switch preventing its contacts from closing or opening correctly.
• Incorrect configuration of the drive's logic input (e.g., Parameter P5-01 set to N.O. instead of N.C. contact).
• Loss of 24VDC supply to the external control circuit, causing all connected inputs to appear open.
• Electrical noise or transient voltage on the logic input line causing a false fault trigger.

Click steps to track your progress.

1. 1

   1. Identify which logic input (e.g., LI3, LI4) is configured as the external fault trigger using the drive's parameter list (e.g., Parameter P5-01).

2. 2

   2. With input power OFF, verify continuity of the wiring from the external device's contacts to the drive's specified logic input terminal.

3. 3

   3. Monitor the status of the relevant logic input (e.g., LI3) on the drive's HMI or diagnostic display while actuating the external device.

4. 4

   4. Check the 24VDC power supply for the external control circuit to ensure it is within specified voltage range.

5. 5

   5. Temporarily bypass the external device (if safe to do so and following lockout/tagout) to confirm if the device itself is faulty.