Trouble shooting grid meter connection & looking into logs related to EMI

[robmeerwijk]

@UpCycleElectric

dmesg -w | grep -E "(usb|ttyUSB|urb)"

You are right, today I did not look into kernel messages. I had before on earlier investigations. But dmesg is clean apart from startup messages.

However I found two links that suggest grounding issues. The first one is this one where Wilm says that a cheap USB-isolater did the trick:

EM540 suddenly not connected anymore

Hi Stefan, I’ve encountered the same issue back in 2023 when I’ve installed my first system with a Multiplus 3000 GX. It seems, there is an isolation issue with the USB-port of the internal GX-device. Tried grounding of the shield an all other suggestions. Nothing had worked so far. A cheap USB-isolator from Ebxx or Amazxx made the trick, Since then, I had no outages. Best, Wilm

The second one suggested not to use terminal 10 at the Grid Meter.

Carlo Gavazzi EM530 Energy meter loses communication

Thank you for all your suggestions. It appears we have found a solution! It involved rewiring the system as follows. Victron prescribes the following when using a Carlo Gavazzi EM530/EM540 energy meter, in combination with the RS485 to USB interface and a CAT5 extension cable: RS485 to USB RS485 Signal EM540 terminal number Orange Data+ 8 Yellow Data- 9 Black GND 10 where Data+/- form a twisted pair. My solution was as follows. I used a CAT6 S/FTP extension cable connect term…

I am not an EMI expert at all, but it could problably explain why it happens under high loads. If the Grid meter picks up EMI, and passes it on to the Cerbo, that could be a problem.