Re: Occupancy detection ?

["Patrick Lidstone" <patrick@xxxxxxxxxxxx>]

--- 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
> Zones to cover all the rooms.
>
> Maybe comfort is a better (expensive) way to go ?
>
> 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