Re: Occupancy detection ?

["Marcus Warrington" <marcusw@xxxxxxxxxxx>]

Patrick,

Thanks for the reply..

So I'm going to have to have double PIRs in each room.. seems wasteful,
I'm surprised COMFORT can't emulate the pulse count itself, i.e. only
trigger alarm if two consecutive detections within a small period of time.

With all this talk of C-BUS, I keep thinking I should bite the bullet and
go for 100% reliability, but I just can't stomach the cost... and if I=20
can't the SWMBO certainly won't !

I'm still unsure exactly how the CBUS stuff hangs together.. why do I
need a =A3400 DIN Dimmer module AND =A3120 switch ? With X10 everything's
i=
n
the module the switch is just a (momentary) switch, I guess that's not
the case with C-BUS.

so 20 lighting zones (inc halls/landings etc) =3D 2 x 8 module dimmers +
1 x 4module dimmers =3D approx =A31200 , PLUS 20 light switches (C-BUS
Coup=
lers)
=3D =A3 1500 , total cost =A32700

20 LD11's =3D =A3600 + 20 momentary switches =3D =A375, total cost =A3675..

I could probably go for the double cost (=A31200) for the dimmer units if
t=
hat
was all I required, but HAVING to have intelligent switches REALLY pushes
i=
t
out of the equation for me.

Marcus

>>> From: "Patrick Lidstone" <patrick@xxxxxxx>
--- In ukha_d@xxxxxxx, "Marcus Warrington" <marcusw@m...>
wrote:
>>>> but what PIR's did people use (I'm thinking of 360degree
ceiling ones)
>>>> and what did they use to interface to the PC ? I need
about 20 PIR=20
>>>> Zones to cover all the rooms.
>>>>=20
>>>> Maybe comfort is a better (expensive) way to go ?
>>>>=20
>>>> I assume cat5e should be more than adequate for connecting
the PIRs
>>>
>>>cat5 is fine for connecting PIRs, although the screw
connections are
>>>better suited to conventional multi-strand alarm cable.
>>>
>>>For occupancy detection, do not use security PIRs. These are
optimised
>>>to avoid false triggering, typically requiring two or more hits
within
>>>a fraction of a second before closing the contact (although
this can
>>>be disabled on certain models). This results in a noticeable
delay.
>>>
>>>In terms of interfacing, all you need is a device capable of
taking
>>>the relay closure on the PIR and translating that into an input
a PC
>>>can understand. There is a wide selection of options -
homevision is
>>>one popular choice, and whilst comfort is also equally capable
in this
>>>respect, as I said earlier, don't expect to be able to use
occupancy
>>>PIRs as security PIRs. Comfort can be programmed just to
transmit
>>>change-in-state data, or translate that into X10 activity,
without
>>>generating an alarm. If you are more of a DIYer, you may also
want to
>>>take a look at the VIOM module, which has a number of
>>>computer-readable digital inputs which could be pressed into
service
>>>for occupancy detection, and plays nicely with most HA
software. If
>>>you are planning on using occupancy detection as the sole means
of
>>>lighting control, then I'd recommend a solution which didn't
depend on
>>>a PC alone - they can be unreliable. HV and Comfort both have a
good
>>>track record in terms of reliability, and are capable of
operating
>>>standalone whilst simultaneously passing data to external home
control
>>>systems/PCs.
>>>
>>>HTH a bit
>>>
>>>Patrick