Lyndel -- Sorry, I just noticed this response. I have several TSU-9400 remotes and several RFX9600 serial extenders. I have controlled my old 20-year old DirecTV boxes using serial to USB (on the box) adapters.

I was just wondering if the fairly new C61K DirecTV boxes actually accept and react to serial commands. Was hoping someone actually was controller a C61K box via RS232 within a Pronto environment that is working now.