Simple app under Windows OS written in C#.
First watch this video on YouTube
This program triggers an USB-to-Serial converter's pin to turn on transistor or to toggle a relay module for transmitting from TRX via PTT pin.
It is super-useful when building a Zello Gateway for i.e. PMR446 citizen band. (This is illegal at some places in the EU, don't know how it's in the US, but always respect your local laws!)
If you find this program useful, you can let me know via e-mail. Looking forward...
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See also my club's website (Slovak only) https://integrac.sk