This is almost always a driver issue or a loose cable. Ensure the plug is pushed firmly into the radio’s microphone or data port.
If you see a yellow exclamation mark in Device Manager, you likely need to "Roll Back" your Prolific driver to a version from 2007 or 2008. zastone d9000 programming software
: Install the USB driver before plugging in the cable to ensure proper COM port assignment. This is almost always a driver issue or a loose cable
: A standard LAN (Ethernet) cable can be modified to act as a programming cable if you have an FTDI serial converter. zastone d9000 programming software