With TTA’s prompting and help, I wrote the following.If you have ever used several motion sensors in conjunction with a chime, say maybe one MS14A at the front door and another at the back, how do you know which is causing the chime to sound? My solution follows.
Any feedback is welcome, positive or negative.
WHICH WAY DID HE (DO WE) GO?
October 18, 2006
JimC
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This is just a short story of how I solved a problem involving multiple motion sensors and other line of sight infrared (IR) sensors and knowing exactly which one was indicating motion. This all started when I decided to put in a small fishpond at my old house. The house was in the city where the lots were only 20 feet wide and 100 feet long. For some reason, when my house was built (sometime in the late 1800’s) it was placed on the lot the opposite of all my neighbors. This had the advantage of giving me a very secluded yard as it was bordered on either side by my neighbor’s houses. This also gave me the perfect location for a pond.
As I normally tend to error on the side of caution, I had some real concerns about the small neighborhood children getting into the pond and getting hurt or even worse. The area of the yard where I wanted to put the pond was not easily visible from the street, but the sound of the water flowing over the waterfall was unmistakable and would certainly attract unwanted visitors. Fortunately the bottom of the yard had a high fence and a locked gate. The top of the yard was mostly taken up by my house and a small gate on one side that provided access to my side door and the yard. This at a minimum would need to be secured or at least protected by some type of sensor that would alert me of any intruders.
First Attempt:I tried the obvious and placed a MS14A Motion Sensor near the gate which, with the CM11A Computer Interface, TM751 Transceiver and a SC546A Remote Chime, would alert me if someone opened the gate. I also installed a MS14A near the pond, with another TM751 located near it, as the range of the MS14A would not reach the CM11A located in the house. This worked fine except that on windy days I would get a lot of false triggers. This proved to be more of an annoyance than the wife and I could tolerate.
Second Attempt:The second attempt, which was successful, involved replacing the MS14As with other devices. On the gate, I used a magnetic switch that would provide a switch closure when the gate was opened. This was wired to a PF284 Powerflash Interface which when it received a switch closure would output an X10 signal on the desired unit and house code over the power lines to the CM11A and from there to the SC546A. This worked perfectly.
I still needed to come up with something more reliable than the MS14A for the immediate pond area. What I decided on was a Infrared Photoelectric Beam Type Sensor. I set this up under a cement bench inside a coffee can to protect it from the elements. I positioned it so that it was aimed at a reflector on the other side of the pond. In this position it would pick up anyone that walked along the path going to the pond as well as anyone in the immediate vicinity of the pond. The output of this device was also wired to a PF284 and using the CM11A / SC546A combo would alert me as to the presence of anyone near the pond. As with the gate, this also worked perfectly.
You would think, now I could relax and enjoy the pond. But not yet. There was still one problem. When the SC546A sounded, was it because of motion at the gate or at the pond? Every time the SC546A would sound, we would have to check both locations and, of course, they were in opposite directions.
The Solution:I had the CM11A output the code for two UM506A Universal Modules - one for the gate and one for the pond. Each had its own unit code. To the output of each of the UM506As, I connected a digital voice recorder and playback kit from Radio Shack PN 276-1323. I prerecorded a message on each unit that was appropriate for the location that had the alarm trip ("Motion at the Pond" or "The Gate was Opened"). Now when there was motion that needed attention, we knew which way to go.
This setup eventually grew to include cameras and a cat deterrent, but that is another story.
Poll
