FWD/REV Run Command Input Error

What does EF mean?

This fault occurs when both a forward and a reverse run command are simultaneously active for an extended period (longer than 0.5 seconds). This indicates a conflict in the control logic or wiring, leading to the motor ramping to a stop to prevent damage from conflicting directional commands. It is a critical safety interlock issue.

• Simultaneous activation of both forward (e.g., S1) and reverse (e.g., S2) run command digital inputs due to wiring error or stuck relay contacts.
• Control logic error in the PLC or external controller causing both FWD and REV commands to be asserted simultaneously.
• Faulty or misconfigured multi-function digital inputs (e.g., P2-01 and P2-02) where both are assigned run commands without proper interlock logic.
• Electrical noise on the control wiring causing a momentary false activation of one of the run commands while the other is active.
• Internal drive hardware fault incorrectly detecting both run commands as active, despite correct external signals.

Click steps to track your progress.

1. 1

   Inspect the wiring for the forward (e.g., S1) and reverse (e.g., S2) run command terminals to ensure no cross-wiring or shorts.

2. 2

   Verify the status of the external devices (e.g., push buttons, PLC outputs) controlling the FWD and REV commands. Manually test each one.

3. 3

   Review the drive parameters (e.g., P2-01, P2-02) assigned to the FWD and REV inputs to confirm correct function assignment and logic.

4. 4

   Monitor the actual input states of the FWD and REV terminals (e.g., using the drive's monitor display U1-01) while operating.

5. 5

   Check the PLC or external controller program for interlocking logic that should prevent simultaneous activation of FWD and REV commands. Add or correct interlocking logic.

6. 6

   Temporarily disconnect one of the run command inputs (e.g., S2 for reverse) and attempt to run the other (e.g., S1 for forward) to isolate the issue.