If it is running at 50 RPM then don't turn it on again until it is correctly programed or you will have another one that will be damaged
The GT is a completely different VF Drive, what size is the spindle and what size is the VFD Drive
Spindle spec's
Drive spec's
Your RS485 connection is only for controlling the spindle speed Etc, that is not needed to get the VFD setup and running