Not communicating


the converter is not sending or receiving any signal to the device we have it hooked to (vinyl plotter) Any ideas on why? Its set up as a com port.


Hi Misty,

Thank you for posting your question. Generally when we see this problem it is because the COM port needs to be set in the communications software or the cable between the serial adapter and the device it is connected to is not the right type (null modem or straight cable). You can discover the COM port by opening Device Manager and clicking Ports (COM & LPT). The adapter will be listed as “Prolific USB-to-Serial Comm Port (COMx).” The number represented by x is the COM port. If you don’t see the adapter listed in Device Manager or if COM port is set correctly, but it still doesn’t work, please let me know. There may be other settings that need to be changed.


Hi Misty,

I’m going to close this thread to keep other people from hijacking it. If you have any questions or haven’t been able to get your plotter working with the adapter, please contact directly at our support address at Thanks!