Motion Sensors in Parallel

dgage

Active Member
I recently had an alarm go off at my business, complete with a police roll.  I could see on the camera that no one was in there but not soon enough to stop the police from being dispatched.  When I went in the next morning, it looks like a spider caused the motion sensor to trip.  I sprayed and cleaned all of the motion sensors but wanted to put another motion sensor in the loop so that they both go off before alarming.  I have a DSC Neo alarm that was put in with wired motions (DSC) I think.  I wanted to see about having some programming with a second run of motion sensors but that doesn't appear to be possible based on my research in the Reference Manual.  So I was wondering if there would be any problems with putting two motion sensors in parallel to cover the same area, just from different corners.  I was looking to buy the Bosch Blue Line Gen2 motion sensors.  If needed, I could completely replace the current old DSC motions (were in here before the recent install).  Thanks.
 
Here have run two automously connected PIR's but not parallel connected in the house.  In the 1980's did run multiple sensors parallel connected.  Did also have issues with spiders with first box type motion sensors that were built in to the walls of a staircase.
 
Newer home I did have two false positives trigger the alarm and subsequent police call visit (while on vacation).  Assumed that these were triggered via the sun setting and reflections.  CCTV did record visit and and checking  by police Never happened again over a period of over 10 years.
 
I did upgrade the old wall mounted PIRs to combo PIR / Microwave sensors over time doing one at a time. Not sure if this would help with spiders. For outdoor CCTV cameras mounted high I just spray them down with a water hose. They get spider webs and bird droppings on them. For indoor PIR you could just use a feather brush on a stick to wipe the spider webs away.
 
dgage said:
I recently had an alarm go off at my business, complete with a police roll.  I could see on the camera that no one was in there but not soon enough to stop the police from being dispatched.  When I went in the next morning, it looks like a spider caused the motion sensor to trip.  I sprayed and cleaned all of the motion sensors but wanted to put another motion sensor in the loop so that they both go off before alarming.  I have a DSC Neo alarm that was put in with wired motions (DSC) I think.  I wanted to see about having some programming with a second run of motion sensors but that doesn't appear to be possible based on my research in the Reference Manual.  So I was wondering if there would be any problems with putting two motion sensors in parallel to cover the same area, just from different corners.  I was looking to buy the Bosch Blue Line Gen2 motion sensors.  If needed, I could completely replace the current old DSC motions (were in here before the recent install).  Thanks.
Hi dgage:
 
Yup, we have spiders around here also, and I have had them trip the alarm as well.  You didn't say how old your panel was, but maybe 12 years ago they passed these set of standards for panels called "Security Industry Association CP-01 Control Panel Standard Features for False Alarm Reduction"    On many panels a firmware update gave you these features.  One of the features added was called "Cross Zoning" and how it works is you designate which zones are "Cross Zoned" and a timeout for these zones.
 
How it works is like this. Once one "cross zoned" zone is tripped, the alarm DOES NOT go off, instead it waits for a second cross zoned zone to trip. If a second zone trips, the alarm goes off. If not the timer resets.  I have ALL my motion detectors "cross zoned" and the timer is 3 minutes, I believe.  If someone breaks in, its very likely they will set off multiple motion detectors in a very short time. Just make sure you have several motion detectors and your all set.
 
Its already saved me once. Not spiders but bright sun triggered a detector when my automatic blinds triggered. 
 
Your DSC Neo SHOULD have "cross zoning." Just activate it for your motion zones, and you are set to go.  DON'T put motion detectors in parallel. Cross zoning is MUCH better.
 
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