[mythtv-users] Serial control of D11-500, some data getting to receiver

Jeff Simpson jeffsimpson at alum.wpi.edu
Mon Jan 29 16:12:26 UTC 2007

On 1/18/07, chris at theromeos.us <chris at theromeos.us> wrote:
> I'm trying to use the directv.pl script modified by Jeff Simpson to change
> channels on my D11-500 DirecTV Receiver.  I'm using a Sabrent CUS6M
> USB->Serial Converter.  It seems to be the longer version of the SBT-USC1M
> listed on the Wiki entry for controlling the STB.
> I have two different null modem cable combinations that I'm working with.
> I've enabled hardware flow control using stty for my com port.
> When I execute the script and use on or off the receiver receives the
> command and acts upon it, but then returns a 0xE0 for each response (the
> response is supposed to be a 0xF0).  The receiver will shut on or off, but
> then the script loops through the remaining retries and continues to say
> TimeOut.
> When I try to change channels with the script, the first number on the
> channel gets to the receiver and displays on the screen as if it was typed
> in by the remote, but then the script displays a Time Out error and
> retries the first character again.
> Is anyone aware of any recent changes in the protocol in use by the STB,
> or have any other ideas for what could be causing this behavior?

That's a new one for me. Typically if it doesn't just magically work
when it's all plugged in and set up, it's a problem with the cable.
The fact that you are able to get the first button press to work fine
seems to say that the cable is fine, or at least mostly so.

What options have you tried tweaking as far as baud rate, parity, flow
control, etc? I've heard mixed results between 9600 and 115200 bps,
and various flow control options.

You may be able to modify the script slightly to accept E0 as a
success and have it continue on. If it is in fact working properly,
that is. You may also be able to tweak the delay times between key
presses to see if that helps you.

 - Jeff

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