EL
ErrorLib
Brands
||
  1. Home
  2. Vacon
  3. NXP AFE-II Drive
  4. F51
About·Privacy·Terms

ErrorLib — Industrial Fault Code Library

Disclaimer: ErrorLib is an independent technical reference tool. While we aim for accuracy, always verify with the manufacturer’s official service manuals before performing maintenance on industrial equipment. ErrorLib is not affiliated with the brands listed.

F51

External fault

Vacon · NXP AFE-II Drive

What does F51 mean?

A digital input configured for external fault monitoring has been activated, signaling a fault condition from an external device or system. This is a generic fault triggered by an external safety or monitoring circuit.

Common Causes

  • Activation of an external safety device (e.g., E-stop, safety light curtain, safety gate) connected to a configured digital input (e.g., DI1).
  • Trip condition from an external motor overload relay or thermal protection device connected to a digital input.
  • Fault in the external system's control logic or PLC sending an erroneous fault signal to the drive's digital input.
  • Broken or short-circuited control wiring to the digital input (e.g., between DI1 and COM) causing a false fault trigger.
  • Loss of auxiliary supply voltage (e.g., 24VDC) powering the external device providing the fault signal.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Identify the specific digital input (e.g., DI1) configured as the external fault input using parameters like P2-01 (Digital Input 1 Function).

  2. 2

    Visually inspect and verify the status of all external devices connected to the identified digital input.

  3. 3

    Measure the voltage across the identified digital input terminal (e.g., DI1 to COM) to confirm the active state of the fault signal.

  4. 4

    Trace the control wiring from the external device to the drive's digital input, checking for cable damage or loose connections.

  5. 5

    Review the external device's status indicators or diagnostic messages to pinpoint the source of its fault condition.

  6. 6

    Temporarily disconnect the external fault signal from the digital input (for troubleshooting only) to verify the drive's reaction.

Browse all codes in this manual (34)
Verified technical data. Last updated: April 2026

Related Faults

F1Over current faultF10Line Synchronization FaultF11Line phase supervision
Source: Vacon NXP AFE-II Drive
View Official PDFSearch more codes in this manual