Specifications

Test your device (Transceiver, TNC...) with another program. Check the com port has not
been disabled by the Bios program (see above).
RFI Problems
In some cases, especially on 160m, 80m, 40m at high output power, you may have a
communication error when transmitting. This is caused by Radio Frequency Interferences (
RFI) between your rig and your PC. You should find a hardware solution (see any Handbook)
but please note this is a minor inconvenient: TRX-Manager has been written to automatically
resumes any communication error (except the first one!).
Reinstalling a com port
This is a solution of the last chance but that can be effective sometime. The steps are:
Port on mother board (for expert only)

Remove the defective serial port from the device manager

Reinstall the serial port

Check you BIOS parameters
USB/Serial Interface (or PCI cards)
You can check your equipment with an other software. However, if it passes this test, your
USB driver may still be faulty! (*).
If you use an USB/Serial interface, the following steps are mandatory:

Unplug the USB interface (or the PCI card)

Remove the com port from the device manager

If possible delete the driver manually

Reinstall the driver (to download from the manufacturer's web site)

Restart Windows

Plug in the USB interface (or the PCI card)
(*) Results depend on the way each programmer uses the com port's APIs.
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