ralph

Im in Botswana. The metres here are made by Hexing and they carry the SDS logo. They dont trip out if you reverse feed them, they just bill you for exported power.

good news. My infini 3Kw plus with SDM630 meter is working well and limiting power to the grid as it should be!
The magic in my case was unchecking (taking away the tick) on the 'export to grid' setting in grid tie with backup II mode and also running a new piece of signal cable away from any power cables between the inverter and the meter situated 30 metres from inverter. All my other settings are as per infini , Modbus card and SDM630 documentation.
When I used a piece of signal cable that was running in same conduit as my power cables the infini wasnt getting any comms from the SDM 630 and was only paying attention to its internal current shunt.
I find that if I unplug the RS485 link I get the same effect/fault as using a signal cable that is running in same conduit as power cable.
If I tick the box for 'export to grid' then the infini runs full throttle into the grid with no limitation.
I note that the feed in to grid calibration does in fact work and one can fine tune the 'sweet spot' so that there is virtually no over and undershoot (within approx 100watts) related to feeding back into the grid.
I note the limiter takes between 5 and 15 seconds to react to changing load conditions.
Having driven myself bonkers trying everything else..... I had a hunch the 220V wiring was overowering the piddly litle RS485 signals due to the cose proximity and long paralell run next to power cables. Nex I am going ot order a RS485 wireless link from fleabay and get rid of the wires altogether.
My Infini is working well, but has a vague burning smell - do these units suffer from problems with failing capacitors?
hope my info helps others.
Regards
Ralph