Re: BSC protocol

[Kevin Hawkins <lists@xxxxxxxxxxxxxxxxx>]

Shane Harrison wrote:

>Hi there,
>
>Just implemented a helper app for my Linet lighting system ie. to xAP
enable
>it.  I was using BSC.
>

Great - well done.. I don't know a lot about the Linet system unfortunately

>  I noticed that the Level tag allows for the reporting
>of a ? value where the level is unknown.  However in the other
direction,
>often such devices (as mine is) don't allow you to set a particular
level -
>only "up" or "down".  I can't track the up's and
down's either since they
>can be adjusted internally without outside knowledge.
>
>
So you can't recover (by enquiry) from your lighting system the level of
a given light ??  .. and local changes aren't reported - that's a shame...

>So question is: was there ever any discussion on having a LEVEL=++ type
tag
>value pair.  I notice the xPL basic control schema's do include such a
thing
>for what it is worth.
>
>
Briefly there was but we had an overriding prority of keeping it simple
- and so a few 'features' were not included to the BSCv1.3 spec.   Two
notable ommisions for lighting are the setting of a ramp rate and the
increment/decrement on a level device.    From what you mention above I
wonder how approriate a level device is for your Linet lighting - can it
ever report a level value accurately ?

There are ways around all things though - you could add your own
specific schema to handle increment/decrement or you could add a
parameter into the existing BSC command block that held a dimstep value

eg
{
ID=02
State=ON
DimStep=+7
}

Now this 'dimstep' aparameter will  (should)  be ignored by all
other applications - however there is a risk in a later BSC spec release
that we formalise such a  parameter and then your usage might not agree
with the official version so I recommend people use an unusual parameter
name like DimStep or something (rather than a more generic name like say
Step) .  In response to a 'dimstep' then your device should immediately
send a BSC event message reporting its new level but I am not sure you
can do that in your system - are you always sending '?'  - if so is BSC
the right choice as other BSC capable devices get no useful info re
status from it. ??


Another approach is to not use a level device but a text device and then
you can send whatever you want to it as a text string including say UP
or DOWN or something, this allows for very sophisticated control/states
but I would always stress that BSC is meant for simple devices and more
complex ones should really add their own supplementary schema for their
extra functionality - In my C-Bus lighting for example implements BSC
but also a lighting schema as well for more advanced control..   If you
intend to release the application for others to use then complete
adherence to teh spec is obviously required - for an internal
implementation you might choose a slightly less rigid approach.

Kevin






>Cheers
>Shane
>
>
>
>
>Yahoo! Groups Links
>
>
>
>
>
>
>
>
>
>