RE: Homevision and PIR's

[ian.bird@xxxxxxx]

Hi Malcolm

As I understand it the X-10 PIR scans in a way similar to all PIR units. The ten second bit is the X-10 re-transmit interval. This means the first time you walk into range they pick up movement and transmit a signal. If however this signal is lost it will not send another for ten more seconds.<= BR> I ended up in the past waving frantically in front of the unit waiting for<= BR> the ten seconds to pass and another signal get sent and hopefully the light=
to come on. Very embarrassing in front of visitors and has low WAF factor.<= BR> In my humble experience they are not hugely reliable and take on average about two seconds to respond with all the other delays in a setup like this=
and a fair wind. You can see my exploits and how I got round the problems as Mark said (thanks Mark) at www.mollyology.com then projects and kitchen<= BR> lights.

HV is great for connecting to all sorts of things and beam breaks are just<= BR> one. Congratulations on your new toy.

HTH

Ian

Ian Bird
CibaVision UK Ltd.
Direct dial 01489 775570
Fax           01489 77957= 0


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            &nb= sp;            =             &nb= sp;            Subje= ct:  RE: [ukha_d] Homevision and PIR's     &n= bsp;            = ;            &n= bsp;       
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Malcolm,

Firstly - well done - I congratulate you as a man of obvious good taste and=
discretion in your choice of HA system.

To turn to latency - I think that the biggest problem with the X10 PIRs is<= BR> that they're not "continuous scan". Instead, they scan the zone e= very xxx
seconds. Compared to that, the .5 second delay of firing a pair of X-10
messages  round (one from PIR to HV, one from HV to whichever devices = you
want to control  as a result) is small.

The most consistently succesfull way of approaching that is to have a PIR plug beam break, in conjunction with an HV timer. The beam break plugs into=
a HV  input port.

Basically, what happens is as follows:

- If either the beam break or the timer triggers, turn on the light
- If the beam break triggers, set the timer to 45 seconds, and count  = down.
- If the PIR triggers, set the timer to 10 minutes, and count down.
- When the timer gets to zero, turn the light off.

That means that when someone walks INTO the room, the light comes on
quickly. The trouble is, a beam break can't tell whether it was someone
going in  or coming out... hence it only turns (leaves) the light on f= or 45
seconds.

... if someone was coming IN, then 45 seconds is plenty of time for the PIR=
to catch them.. and when THAT happens, the timer gets 10 minutes to play with...  so the PIR only needs to "re-catch" them every 10 m= inutes.

... if a second person comes into the room, then the timer gets pulled down=
to 45 seconds, but that's STILL plenty of time for the PIR to cut in and wham it  back to 10 minutes.

... if someone leaves the room, the time gets pulled down to 45 seconds, but that's STILL plenty of time for another person still in the room to be<= BR> caught by the PIR.

... if someone leaves the room, and there's no-one left to trigger the PIR,=
the lights go off 45 seconds later.

Now, in a "destination room", then this is simple, 'cos there's o= nly only
doorway, and hence only 1 beam break.

In a "circulation room", it's harder, 'cos you need a beam break = per
entry.

See www.mollyology.com for more  details on beam breaks.

M.
-----Original Message-----
From: Malcolm Passmoor  [mailto:malcolm.passmoor@xxxxxxx]
Sent: Fri 04/10/2002  12:47
To: ukha_d@xxxxxxx Cc:
Subject:  [ukha_d] Homevision and PIR's


Hello folks,


Just in case you remember my name from a previous  posting, I was the = chap
having some trouble in deciding whether to go for  something like
homeseer/cm12u or homevision - well I went for homevision and  so far = I
haven't really done much with it - x10 stuff can be quite expensive  t= o
accumulate!

Any way, my first project is to do the "movement  in the hall=A0-= lights on"
thing and I heard some comment that the wireless  X10 PIR/transceiver = set
up presents a bit of a lag in terms of response times  - is this true?= To
cut a long story short and since I have HV with all of it  IO capabili= ties
I bought a relatively inexpensive response systems wired PIR - trouble is there are no installation  guide and I'm a bit of an electronics novic= e -
please please  help.

The PIR is a 12v unit so I found a 12v PSU and  connected it the
appropriate terminals - its seems to flash when there's  movement so I=
guess so far so good. I was assuming that I should now connect  the N/= C
terminals to port B on the HV to pin and ground - Am I right - HV''s a = ; bit
pricey and I don't want to try it and fry it. Any help  appreciated.
Malcolm.

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