BSC v1.3 xAPBSC.cmd thoughts...

[Kevin Hawkins <lists@xxxxxxxxxxxxxxxxx>]

Given BSC v1.3 is now released I would like to raise a discussion topic
here.....

In the BSC v1.3 spec it is implicit that a xAPBSC.cmd messages sent to a
level based device should contain both a 'state' parameter and a
'level'  parameter..   this was not my intention .

I think it should be allowable within a  xAPBSC.cmd message that these
parameters should be optional - if they are absent then the previous
value is retained. Normally of course one or both parameters will be
present to perform any useful function. For example to turn a light on
you should only have to say "State=On"  and it should action this
based
on its current stored dim level.  Likewise you should be able to say
"Level=50%" and this will alter the light level without changing
the
state of the light from Off to On or On to Off.  If your intention is to
change both the Level and the State then you should include both in the
xAPBSC.cmd . Part of this is really saying that a 'binary' state command
eg from an ON/OFF switch  sent to a 'level' based device eg a light
dimmer must work correctly.

It should be noted that if a device is currently ON at 50% and you turn
it OFF and then ON again it may not come back on at 50% . For example
most X10 hardware behaves badly this way. Normally I think a device
should endevour to persist its last level between ON and OFF transitions
as most real world devices work this way.

This leads to an ambiguity - when you turn an ON (at 30%)  device OFF
should it report its status now as OFF at 30% or OFF at 0%  ???   My
initial thoughts were the former (as this now provides an indication of
what level it will come on at again if it was sent an ON command)...
however some X10 hardware will still behave badly as turning an ON 50%
device to OFF would have to report an OFF 100% status ,(as it will come
on at 100% next time).   If alternatively you report the true status ie
OFF is always 0% then how should you respond (xAPBSC.event) to a
Level=60%  command sent whilst a device is OFF   ..    Thoughts ???

Note however when reporting the status of a device using  xAPBSC.info or
xAPBSC.event messages then it IS mandatory that both the 'State' and
'Level' is reported as it will always be known.

Kevin