James / Mike,
The relay I'm using (which are abundant here in the US - very different than the 'MagiDeal' USB relays that they have in the U.K.) has the following qualities:
The USB relay I have (and bought off EBay and they're also on Amazon) acts like a COM port device and requires the following command strings to engage/disengage the relay:
ON = 0xA0 0x01 0x01 0xA2
OFF = 0xA0 0x01 0x00 0xA1
...meaning, that if the relay was seen by Windows as a COM6 device, you would send the PTT-ON string of: 0xA0 0x01 0x01 0xA2 ..on COM 6. and similarly, you'd send the PTT-OFF string of: 0xA0 0x01 0x00 0xA1 on the same COM port, COM 6.
All I'm looking for is a way to do this when SDRAngel enters transmit such that the relay can switch over from the Rx1W port on the Lime to the Tx1L port.
Also, if an application is running - like WSJT-X - currently there are no 'radio' provisions to make SDRAngel receive or transmit from that app (WSJT-X). I suppose one could hijack the serial port commands for any radio (let's say, Kenwood) and then look for the PTT command somehow from the app communicating to (presumably) a COM port that's been set up in the app (again, WSJT-X). That would be the way to fire the PTT relay and I would think there's got to be some way of taking the transmit and receive and start/stopping those to get half-duplex. This is where my research is at the time, but I'm not savvy enough with the REST API to make any of this happen right now. I could just as easily do all this in hardware just using the Line-Out function of the PC when WSJT-X wants to go into transmit and have the relay switch to the right port, but it means that the transmit function has to run all the time in SDRAngel and you only use USB and the audio from Line-Out to make the whole thing work.
...Wish there was a way to do this through 'Angel...It would greatly simplify this whole issue.
73 de Marty KN0CK