Re: CBUS & Comfort Questions

[Kevin Hawkins <lists@xxxxxxxxxxxxxxxxx>]

Indeed it is possible to inform C-Bus using the interface that a
'virtual' group has changed level, I use the same interface module as
Comfort for my xAP or HomeVision gateway and do this. However C-Bus
doesn't maintain this information unless it has a real group present,
for example a channel on a dimmer or relay pack. It does pass this
information around the whole network at the time of the change though.
C-Bus is very clever about it's state synchronisation and all units
constantly exchange information about what they believe is their current
state . There are even very clever arbitration arrangements such that if
a C-Bus network does become segmented/disconnected for a while and then
rejoined (with group discrepencies)  they can 'discuss' the best outcome
for group synchronisation .  You can see this at work should you
disconnect a switch and change some groups  and reconnect it - within a
few seconds all the indicators on the switch will change to match the
current group status :-)

The group level information is maintained and exchanged by C-Bus
output units - dimmer/relay channels (packs) - and as there wouldn't be
a matching one on C-Bus for say a Comfort relay then it is not reported.
To all intents and purposes it doesn't exist.  Even if you send a
command or status to the 'virtual' group on C-Bus it doesn't maintain it
as it really has no need to . However of course you could pick this up
in a controller on C-Bus  like the PAC or the touchscreens and store /
use it.  This layer of smart control on C-Bus is an extra sophistication
that those with more sophisticated needs will use ( logic, scripts,
timed events etc). It is not possible, or really needed,  to
artificially maintain this group state information externally via a
C-Bus serial or Ethernet interface.  Commercially it also precludes
anyone making externally attached fully integrated dimmers/relays for
C-Bus ;-)

Kevin


Phil Harris wrote:say
>> Do you know why they dont Phil ? Limitation of the design or
choice ?
>>
>
> The "bridge" that is used by the Comfort to C-Bus UCM is
more than capable
> of reporting data both ways (the Comfort to C-Bus UCM uses a standard
> daughterboard which is used in other applications) so I would assume
it's
> simply that either it was decided that Comfort wouldn't report back
its
> state changes to C-Bus (assuming that a Comfort I/O port is mapped
directly
> to a C-Bus group) or somehow Comfort couldn't do it (which I doubt).
> Certainly the hardware interface to C-Bus is perfectly capable of
doing
> this.
>
> Phil
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