yalang yl620 VFD rs485/modbus communicaiton

I recently spent two days trying to get RS485 working with this VFD before giving up. It appears to be simply reject any communication on that external port no matter what settings are made. My reports in this thread might be interesting, but there's nothing good: forum.linuxcnc.org/24-hal-components/387...-rtu?start=60#218634

I would suggest just using PWM control, takes about 10 minutes to set up. If only I had a time machine...

I read somewhere that while the HuangYang VFDs do not talk modbus, this Yalang one actually does, and my experience with the logic analyzer and message interaction would agree. The messages it returns are well-formed modbus and consistent. The LCD control panel connection also uses standard modbus, but at a fixed baud rate (38400 in my case) that is not user-configurable. I used the logic analyzer to watch the traffic between the LCD panel and the main board, and when I imitate the panel my messages are responded to correctly, but the motor never moves.

As for the usual RS485 port, it always responds with "Illegal data value" no matter what, even when only attempting to read. I wrote a script that tried to read all registers from 0-16384 and every single one failed with the same result. It's almost like the firmware is either bugged or never intended to accept traffic on that port in the first place.

Does your line need termination resistors?

FYI, I got the YL620-A working on RS-485. Andypugh was right, just swap the RS-485 A/B wires. The labels (silkscreen) on the VFD PCB are incorrect.

Hey, can you let me know how you got it working? I am having issues. I used vfdmod, the integrated driver, but in no way I get it working.

Got it working. Please see attached my files, in case someone else needs them.

Does anyone know what the registers for Amps, Voltage,... are in the YL 620? Or if not, how to find that out?