I just received my Digirig, and I was successful at getting it to work with an Icom HT. When I tried using it with a Yaesu FT-818 in Winlink & VARA HF, the radio immediately went to a constant transmit. In the Radio Control Port section in the Winlink HF Settings window, I have RTS enabled. Disabling the RTS will stop the constant transmit, but then I am unable to transmit through CAT control. Disabling DTR while RTS is enabled had no effect. The only way I can transmit is to select the same Com port under PTT Port, but I believe this shouldn’t be necessary and something went wrong somewhere. I am using a Windows 10 laptop with the latest Silicon Labs driver installed.
I tried Com9 which is what Windows assigned to the Digirig as well as Com10 (set in device manager), and I tried 38400 and 9600 baud. Did I miss something?
I can’t claim to be an expert, and I may be wrong on this, but here are my thoughts.
Historically, when interfaces worked over 9 or 25 pin RS232, software sometimes needed to assert the RTS line constantly to +12V in order to power the interface. With Digirig being powered via USB, this is not necessary in our case.
Digirig can use RTS (from its CP2102 UART) to tell the radio to Tx which is possibly why you have your problem. Alternatively to RTS, CAT can also be used in order to make the radio switch between Tx and Rx modes.
I don’t know Winlink, but for instance when configuring FLRig, configure PTT method for either RTS of CAT. Uncheck Force Control Lines in order to prevent the software from asserting +12V on RTS.