Thousands of people are using Huanyang VFD's with modbus plugins, so I don't believe that modbus support in the VFD has been an issue for many years
Gerry, I hope that is correct. But as far as I know Mach 3 only works with HuanYang VFDs using an unsupported, closed source driver.
I have not found any instructions for setting up Mach 4 with a HuanYang VFD.
The Mach 4 documentation does not cover modbus -- the "Mach 4 Scripting Manual" ends with a heading reading "Modbus" with no content following it.
I'm not trying to be snarky, and I would love to have answers to any of the three questions I asked in my original post.
I'm an experienced software developer and I have the documentation for HuanYang VFDs -- if there is any documentation about writing modbus drivers for Mach4 I would be interested in having a crack at it.