| Error Message | Cause | Solution | |----------------|--------|-----------| | “Radio not responding” | Wrong COM port, bad cable, radio not powered | Check power, try COM2, replace cable | | “Checksum failed” | USB timing or corrupted codeplug | Use native COM port or FTDI adapter | | “Model mismatch” | Using Plus software on Standard radio (or vice versa) | Download correct RSS/CPS | | “Out of band” | Frequency outside radio’s range | Realign radio or use software band-extension (not recommended) | | “Serial port in use” | Another app (GPS, modem) occupies COM port | Disable other serial devices |

DOSBox is a free emulator that recreates an MS-DOS environment on modern computers. Download and install DOSBox. Mount the folder containing your GM950 RSS.

: A compatible cable, such as the MaxtonData RPC-MM-U , is essential. Some cables may require an external 9V battery if they act as a standalone Radio Interface Box (RIB). Port Configuration : Go to Device Manager on your PC. Set the cable's COM port to COM1 .