i have a Multiplus 2 GX system running since more than half a year now, including a Pytes V5a battery and a Huawei inverter. Recently, i noticed, that only L1 of the grid is visible in the dashboard. The EM540 (connected via USB-RS485 converter) is not connected.
Due to that, the system is in “pass through” mode.
I checked the smart meter by plugging the USB converter into my computer and could set up a connection with Carlo Gavazzi UCS immediately without any issue. Also the values seemed to be correct. This means, that the EM540 and the USB converter seem to work fine.
Now there is also a very strange behaviour in the Multiplus 2 GX: when i reboot the device, the connection to the EM540 is stable for like 10 or 20 seconds after rebooting. During this time, everything works just fine, after that, the connection is lost. From time to time, the mode changes from pass through to feed in for some seconds, only to change back to pass through again.
I tried several things, like deleting the EM540 from the device list, adding resistors to the RS485 wiring (which was not necessary for the last 6 months…) and i even bought a new RS485 converter. All without any success. Has this happened to anyone else in the past? Is there a solution for this?
Thanks for your answer! Meanwhile i found another thread, where a user had a similar problem.
I tried the solution from this thread (connecting the patch cable shielding to ground, rather than connecting ground from EM540 to the USB converter ground). It seemed to help, but i had one connection loss during the day. May be due to insufficient connection to the patch cable shielding, i will try to improve that by soldering).
For me, it is still strange why this happened after half a year. Nothing has changed on the system, before it was perfectly stable, now it seemed almost impossible to make it run for a while.
I once had a similar temporary problem with the connection to the grid meter, in my case, the em24. I almost went crazy because it always occurred temporarily. In my case, it turned out to be a lack of shielding from other cables, especially DC cables. Could it be that some parallel cables were carrying more current than before in the past sunny weeks? This is just a guess based on my own experience.
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.
@Sarowe1990 in my case, there are no DC cables close to the Multiplus besides the battery connections. There have been no high peaks in current in the last months. Therefore i don’t think this is the reason in this specific case, although it would be a reasonable explanation.
@Wilm this sounds very interesting. I totally forgot, that this was the solution for unstable USB connections on my DIY milling machine as well. Somehow i didn’t think of that. I will definitely try this, thank you very much!