Communication Error
Beckhoff · EL6900 Operating Instructions
What does Diag3:off, Diag4:2_pulses mean?
This diagnostic flashing code (Diag 3 off, Diag 4: 2 flash pulses with longer pause) indicates a communication error within one of the TwinSAFE groups. This suggests issues with data exchange between safety devices on the EtherCAT network, potentially due to faulty wiring, incorrect addressing, or timing discrepancies.
Common Causes
- A communication failure has been detected between the device and its master or other connected devices.
- Loss of signal or data integrity on the communication bus.
- Timeout on expected communication messages from a peer device.
Repair Steps & Checklist
Click steps to track your progress.
- 1
Verify the EtherCAT communication status of all TwinSAFE slaves connected to the EL6900 in the TwinCAT System Manager, checking for lost frames or slave state changes.
- 2
Inspect the EtherCAT cables and connectors for damage, proper seating, and correct shielding between the EL6900 and connected TwinSAFE slaves.
- 3
Check the EtherCAT network topology and addressing configuration in TwinCAT to ensure it precisely matches the safety project setup.