DirecTV d12-300 Serial Control

[kd5crs]

Once more unto the breach!

I've read every topic I can find about D12-300s, DirecTV serial control in general, and I'm almost ready to pull my hair out because it just won't work.

Hardware: I have usb to serial cable -> serial null modem cable -> serial to usb cable -> cable box. The usb to serial cable shows up as COM 3 in device manager. SageTV finds the PVR-250 fine, set up for S-Video, DirecTV serial control, COM 3. Picture and sound are great, but channel does not change. I set the com port speed to 9600 baud.

Driver: I've tried both the driver that comes with V6 and the "old" driver. Neither works. In the debug file, I see a statement saying "incomplete COM read" when it tries to change the channel.

DirecTVSerialControl.exe: Does NOT work, and shows a timeout after every command.

Box: I have rebooted it with the usb cable in, and with it out. Neither works.

So, any suggestions? The usb to serial cables I got show up as made by Huge Pine in the device manager, are these known to work or not to work? I'm using a null modem serial cable instead of the F/F null modem, is this known to work or not work? If DTVSerialControl.exe doesn't work, does that mean for sure it is a hardware problem? It connects to the COM port 3 just fine.

Is there anyone who has my exact setup working? (Windows XP, D12-300 stb, usb on both ends, SageTV v6)

Thanks.
Brian

[toricred]

Do you know the chipset? What is the name of the driver? Directv only officially supports a couple of controllers for the USB to serial devices.