[mythtv-users] Changing channels on a new D11 directv receiver

Brian Wallen brian_wallen at hotmail.com
Fri Dec 30 11:05:30 EST 2005

Ok, I've read the guide you wrote up on mythtv.info.  My problem is, I can't 
envision how this works.  First off, what is the difference between a null 
modem cable and a serial cable, and when I'm looking at one, how can I tell 
which kind it is?

Secondly, where does the usb->serial adapter plug in?  The way I'm seeing it 
now is I plug a usb cable into my receiver.  Then on the other end of that 
cable is the usb->serial adapter.  Then on the serial side of the 
usb->serial adapter goes a null modem cable that will plug into the serial 
port of my backend.  Is this anywhere close to being right?

And lastly, how would I change channels using one backend and 2+ directv 

>From: Jeff Simpson <jeffsimpson at alum.wpi.edu>
>Reply-To: Discussion about mythtv <mythtv-users at mythtv.org>
>To: Discussion about mythtv <mythtv-users at mythtv.org>
>Subject: Re: [mythtv-users] Changing channels on a new D11 directv receiver
>Date: Fri, 30 Dec 2005 10:09:03 -0500
>On 12/30/05, Brian Wallen <brian_wallen at hotmail.com> wrote:
> >
> > Yesterday I just got directv in my house.  I have a couple of d11
> > receivers
> > with usb ports in the back.  The usb port is the regular rectangular 
> > like the ones in the back of a computer.  Is it possible to have a cable
> > that has two rectangular ends and use that to control the receiver?  I 
> > one guy say he got it working with a usb->serial converter, but I wanted
> > to
> > see if that was my only choice or not.
>It is possible to have a cable that has USB on both ends....but that cable
>will be made up of a USB->Serial, a Null-Modem adapter, and a Serial->USB
>again, all connected together with electrical tape :-P
>The issue is that the USB port on the computer and the one on the STB are
>both host usb - and just like with two PCs, you can't just plug a USB
>male->male cable in and connect them. With serial you could do that, 
>serial is a "dumb" technology - it knows nothing about how it is to be 
>and expects the computer to know it's there and connect to it. USB, on the
>other hand, requires that devices have circuitry in them so that they are
>detected by the host computer as a particular type of device so that the
>host knows what driver to use and how to access it. Since both ends are 
>they both need to be able to find that kind of circuitry, so there needs to
>be two USB->serial adapters.
>If the cable company decided to redesign the STB, it would make sense for
>them to make it so that the USB->serial conversion is done inside the box,
>so that you can just plug in a USB extension cable to use it. Problem there
>is that you wouldn't be able to use it with a standard serial port anymore,
>so a lot of their test equipment wouldn't be usable.

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