Mark
I tried everything you said.
i entered some crazy numbers in the debounce box (100000000), also changed my connection from T to S,
disabled Modbus spindle, disabled all the other inputs but still nothing.
The only thing i noticed is that (and i don't know why) when i press F5 now thw spindle starts Mach3
doesn't freeze (i can turn on coolant for example), but when i press F5 again for stoping the spindle
i get this message and then Mach3 freezes again and i have to disconnect the usb cable to get back to normal.
this is the message i'm receiving

Could it be that my USB to RS485 cable is the G version and not the F ?
I mean the way i see it is that somehow i can send signals to the VFD but not receive.