Dan,
Not sure if it's possible, but it might be a good idea to let the user define the field number for the Sact. Otherwise, at some point, you may see conflicts with screensets or other plugins. I use 50 different fields in my 2017 screen, but I start at 20300, so there's no issue there. But I've already changed some numbers in my screen due to a confilct with another plugin.
Just a thought.
Now, the question is, are all Huanyang VFD's on Ebay the same, and will they all work with the plugin. I guess it would be worth spending the extra $30 to get one that claims to be the real deal?
UPDATED 2.2KW VARIABLE FREQUENCY DRIVE INVERTER VFD 220V 3HP 10A HIGH QUALITY | eBay