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Diag3:off, Diag4:3_pulses

Function Block and Communication Error

Beckhoff · EL6900 Operating Instructions

What does Diag3:off, Diag4:3_pulses mean?

This diagnostic flashing code (Diag 3 off, Diag 4: 3 flash pulses with longer pause) signifies both a function block error and a communication error within one of the TwinSAFE groups. This combined fault suggests issues with both the internal logic processing and the external data exchange within the safety system, indicating a complex problem requiring thorough investigation of both aspects.

Common Causes

  • Both an error within a function block and a communication error have been detected simultaneously.
  • The function block error may be a consequence of communication issues, or vice versa.
  • Complex failure involving both application logic and network connectivity.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Address potential communication errors first by verifying EtherCAT cabling and slave statuses in the TwinCAT System Manager.

  2. 2

    Subsequently, investigate TwinSAFE function block parameters and logic within TwinCAT, checking for invalid states or unexpected outputs, similar to a 'Function Block Error' scenario.

  3. 3

    Review recent changes to the safety project or hardware configuration that could simultaneously affect both communication and safety logic execution.

Browse all codes in this manual (16)
Verified technical data. Last updated: April 2026

Related Faults

0005 hexMaximum Temperature Exceeded0006 hexTemperature Fell Below Minimum0007 hexTemperature Difference Exceeded
Source: Beckhoff EL6900 Operating Instructions
Open Manual (Page 54)Search more codes in this manual