[mythtv-users] Frontend USB to TV RS232 serial?

[Brian Wood]

On Monday 03 August 2009 17:40:32 Paul Bender wrote:
> mythtv at derdev.com wrote:
> > On a frontend without any available serial ports (RS232) and plenty of
> > available USB ports, is there an easy/obvious solution to connect the
> > frontend to an HDTV's RS232 serial port for power on/off control?
> >
> > I see lots of USB to Serial converters but they don't seem to terminate
> > in the male serial connection needed to link up to the TV...  Barking up
> > the wrong tree here?
>
> I connect to my Sharp Aquos HDTV using a USB-to-RS232 cable along with
> an RS232 null modem (aka gender-bender) connector/cable.

There seems to be some confusion about the difference between a null modem and 
a "gender bender".

A null modem swaps the txd and rxd lines, as well as the handshake lines (if 
it's a good one), thus changing DTE to DCE or vice versa.

A Gender bender is simply a male-to-male or a female-to-female, to change a 
connector of one gender to the other.

It's true that in most serial cases gender tells you if the connector is DTE 
or DCE, but changing the gender is not the same thing as changing DTE to DCE, 
though some null modems do change the gender as well.

DTE = Data terminal equipment, like a terminal or a computer.

DCE = Data communications equipment, like a modem.

DTE can't talk to DTE without a null modem, straight cables can be used only 
to connect DTE to DCE.

-- 
Brian Wood
beww at beww.org