Adding message to add my experience to the knowledge base, in case in might be useful for anyone. In brief...
In more detail:
1 - Worked fine in Windows 10, I think. But I was having problems with my laptop (crash to desktop, losing connection with AXBB, couldnt resolve any of it) so I built a desktop from old gaming components, installed windows 7, and quickly started getting "index outside the bounds of the array" errors thrown up relating to this plugin. Mostly I could just ignore the error, but after a couple of days it came up again, I hit continue and UCCNC lost connection with the inverter. Reinstalled software, .net framework, rolled back .net to previous version, none of which helped. Fortunately I had other USB RS485 adaptors to try, as in the past I'd had a lot of issues with #2 adaptor randomly dying after a month of two of use when using mach, so I'd stocked up on different models.
2 - Tried this next, connected fine, span up and span down, spindletalker also happy. But at the end of my first cutting program, the spindle didnt spin down, and UCCNC had lost connection.
3 - Requires different drivers, different chip manufacturer (FT232R chip). 2 days in right now and all good, no error, no disconnections etc.
So, if anyone has problems, especially in windows 7, suggest trying adaptor #3 above...