EFB comm loss

What does 6681 mean?

Communication has been lost on the embedded fieldbus (EFB). This means the drive is no longer receiving or sending data to the fieldbus master, leading to loss of control or monitoring via the fieldbus. Critical control functions may be disrupted.

• Physical disconnection or damage to the embedded fieldbus (EFB) communication cable (e.g., Ethernet, RS-485) at either the drive or the master end.
• Fieldbus master controller is powered off, in an error state, or has stopped transmitting data to the drive.
• Incorrect EFB network address (e.g., Parameter P7-01 EFB Address) or baud rate (P7-02 EFB Baud Rate) configuration in the drive or master.
• Faulty EFB communication module (internal to the drive or a plug-in option) preventing proper signal transmission/reception.
• Improper termination resistors (e.g., 120 Ohm for RS-485) at the ends of the fieldbus segment, causing signal reflections.

Click steps to track your progress.

1. 1

   Verify the physical EFB cable connection at the drive's fieldbus port (e.g., RJ45, screw terminals) and at the fieldbus master/PLC.

2. 2

   Check the status indicator LEDs on the drive's EFB port and the fieldbus master for link activity, data transmission, and error codes.

3. 3

   Measure the voltage across the data lines (e.g., A/B for RS-485) if applicable to ensure signal presence and integrity.

4. 4

   Confirm that the drive's fieldbus address (e.g., P7-01 EFB Address) and baud rate (e.g., P7-02 EFB Baud Rate) match the fieldbus master's configuration exactly.

5. 5

   Inspect the fieldbus network for correct termination resistor placement and values (e.g., 120 Ohm at both physical ends of an RS-485 bus).

6. 6

   Temporarily connect a fieldbus analyzer tool to the network to diagnose communication traffic and identify the source of data loss.