Re: DMX and xPL

["Mal Lansell" <mlansell@xxxxxxxxxxxxxx>]

I think the basic problem with your plan is that the xPL design expects
there to be an xplHal (or other message processing equivalent).

As far as I can tell from the docs, xpl devices never send commands
directly
to each other - xplHal sends all the commands, based on scripts and the
trigger messages it receives (someone PLEASE correct me if I'm wrong about
this - it's pretty fundamental!)

So, a light switch sends a trigger when it changes state (using
sensor.basic - control.basic has no trigger form).  xPLHal picks this up
and
sends commands to lights etc according to the scripts it is running.

Having said that, I don't see why you couldn't have your lightswitch send
both control.basic commands (to the light) and sensor.basic trigger
messages
as you suggest.  You would just have to not script xplHal to send commands
to the lights as well ;-)

Mal






----- Original Message -----
From: "g8kmh" <lehane@xxxxxxx>
To: <ukha_xpl@xxxxxxx>
Sent: Monday, October 25, 2004 7:54 PM
Subject: [ukha_xpl] DMX and xPL


>
>
> There does seem to be a lot of DMX information and equipment about.
> So it would seem a good starting place for lamp dimmers, which at a
> low level is probably one of the more useful HA functions. There is
> the schematics and code for a PIC at
> http://www.geocities.com/ph_zone/Digi_Pack/Digi_Pack.html
and this
> could be extended to more channels easily, as well as ditching some
> of the other features. Secondhand units also seem to be reasonably
> available at lower prices per channel than C-BUS.
>
> Philoshically it would be ideal to extend xPL onto dumb devices. A
> couple of downsides to a PC based parser revolve around the fact that
> a light switch (say) will need to send a message to the parser and
> then the parser (or script/determinator) will resend it back out. No
> PC, software or microcontroller = no lights. With xPL on the, say,
> CAN bus then a switch could be configured to send an xPL command to
> the lounge lights also on the RS485/CAN bus but also picked up by the
> PC interface and used to run scripts, etc. Yes, the switch would need
> enough smarts to be able to be configured but that's not too tough.
> Now, that kind of breaks the xPL schemas since a switch should use
> sensor.basic - is it 'legal' for a switch to issue a control.basic
> command as well as a sensor.basic trigger?
>
> CANbus does start to look attractive and vscp or yasp as the low
> level protocol, although I'm sure there are others!
>
> The reason for the original point was that we're doing major building
> works and an extension next year so have a clean slate. X10 isn't on
> the shopping list :)
>
> Lehane
>
>
>
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>
>
> xPL Links: http://www.xplproject.org.uk http://www.xplhal.com
http://www.xpl.myby.co.uk
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