Cerbo GX doesn't list connected EM540

[BerndM]

My system: PV with micro inverters feeding my home consumer and export excess to grid, since two years. Recently BYD 12 kWh, MP2 3000 one phase, controlled by Cerbo GX, supported by EM540 installed. EM 540 functions metering import and export, but doesn’t show up in Cerbo GX, hence ESS doesn’t function properly, only charging battery ok, when external energy meter is disabled. From EM540 to Cerbo GX USB-RS485-WE cable from Victron.
My checks done:

1. Cable RS485 at EM540 correct (orange - 8, yellow - 9, black - 10)
2. EM540 reset to factory (baud 9600, measuring C, parity no, stop bit 1)
3. Cable way (about 20 m) tested ok
4. USB-RS485-WE cable direct, i.e. 1m length, from EM540 to laptop and data flow at USB port analyzed with software (Device Monitoring Studio and redundantly Serial Port Monitor) - no data flow from EM540 detected
   Does this mean that either the USB-RS485-WE cable or the EM540 is corrupted?

Can anybody experienced confirm or give advice to solve the issue?
I would very much appreciate any contribution.
BerndM

[ricardocello (Rick)]

Try swapping the A and B RS-485 lines (8 and 9, polarity could be wrong).
Try adding a wire combining EM540 connections 7 and 8 to add termination resistors.

At boot, the Cerbo tries to talk to the USB serial devices.
See if anything is being transmitted if you have the tools to do so.
This will confirm that the Cerbo recognizes the USB serial port and is scanning for Energy Meters.

[BerndM]

Thanks for advice. I testet them without success.
Nevertheless these last tests focusing on cable way made me thinking further, so I did this morning another test, discarding the 20 m cable way and distrusting my analyzes with USB port software. I connected Cerbo GX with a short USB-RS485-WE cable to EM 540, what I didn’t do so far due to fairly much preparations to provide DC to that place, and IT WORKS as it should do. Conclusion: my 20 m cable way has to be reconfigured, what I will do next days.
Thanks