OK, I am sorry, I don't know what's going on. I made some CRC16 calculations
using this calculator but it seems that the checksum is right, so it can't be the CRC, something else must be wrong. Note that the checksum is in reverse order, so when your checksum says 82 D0 it is actually D082, which is as it supposed to be. I compared with some examples from my manual, just to check the calculator, and the calculator results match that of my manual.
Perhaps you can send a PM to member vmax549. He says in
this post that he is using Modbus with HY. Perhaps he can help you sort it out.
Sorry for not being able to help.
Just a little side note... Yesterday I managed to control my VFD via Modbus even with UCCNC. Modbus support is much better there, although I have some minor issues, which I informed CNC Drive about. I modified M3, M4 and M5 macros as well, so that the G-code execution stops after M3 and M4 until the spindle speed is reached, and also after M5 until the spindle is stopped. This removes the need of fixed dwell time for acceleration and deceleration, which I think is good and useful. My UC300ETH has arrived, I have to collect it this afternoon, and after that I will play with the UCCNC a bit more seriously. Currently in demo mode, and in demo mode motion is not supported, only simulated. It needs the UC300ETH, since the license is for that controller, not my UC300USB.