You might find that after upgrading to Fldigi 4.1.20 that GPIO PTT does not work. That’s most likely because you haven't initialized the GPIO settings (new in this version).
Click Configure > Config Dialog > Rig Control > GPIO. **FOR THE RIGHT RADIO** set it up like this. Then click Initialize.
**FOR THE LEFT RADIO** set it up like this. Then click Initialize.
Steve
AG7GN