Added a keypad, caused a false alarm (?)

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Old 05-29-19, 10:08 PM
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Question Added a keypad, caused a false alarm (?)

About 1.5 years ago I installed a DSC PC5010 v4.6 with three keypads and a hardwire zone expander. All but a couple zones are hardwired with quality switches, quality cable, SEOL resistors, soldered connections, etc. Everything has worked flawlessly since day one. I've installed about half a dozen of these systems for myself and friends and never had an issue or any false alarms.

This past weekend, I installed another PK5500 keypad I purchased used from eBay about 10 feet from an existing keypad (I wanted one on both sides of the door to the garage). I tapped into the keybus wiring from the existing keypad, powered the panel back up, and all was well. All new connections were soldered.

About 9:00 p.m. I armed the system like every other night then went to sleep. About 11:00 p.m. the system goes into full alarm and shows two doors open. Both of these doors are on their own zones, so two zones violated. When I finally go check the doors are both closed and chime the keypads when I open/close them. I removed the new (used) keypad and rearmed the system. No problems since.

Any idea what would cause this? This system has never had issues until this keypad was added and since I removed it, all is well. The door switches have over an inch before they break so it's not a switch operating at the edge of its envelope or anything like that. The only thing that's changed was the keypad.
 
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Old 05-30-19, 07:06 AM
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I won't say it's _impossible_ for a new keypad to cause a false alarm on unrelated zones, but I don't see how; unless you're talking about a keypad that incorporates zone expansion. If your existing keypad by the door to garage is used for zone expansion, this would be the time to mention it. Otherwise, it could be pure coincidence that the zones happened to fault (be violated) right after adding the keypad.

One single false doesn't establish a pattern, so no subsequent falses doesn't necessarily mean anything. There might have been no more false alarms if you had left the new/used keypad in place. Some false alarm problems are intermittent like that.

It might be useful to know what zones falsed, i.e., were they both expansion zones, or of the panel's 8 on-board zones?

It's good that you can tell us the distance between switch and magnet. More importantly, how far can you crack the door open before the zone opens? I try to set it so I can move the door at least half an inch, and an inch isn't too much if it doesn't show daylight through the crack. All houses shift a bit occasionally, and sometime shift more than other times, making falsing very intermittent.

TBH, I haven't worked with DSC regularly for over a decade, so other pro's on here might have more insight into your situation.
 
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Old 05-30-19, 02:38 PM
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Also, did you give this new keypad it's own unique address?
 
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Old 05-30-19, 04:09 PM
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Both zones are on the zone expander.

The magnet/switches are maybe 1/4" apart and perfectly aligned. I can open the door a good inch before tripping either door. I'm certain this isn't a bad switch or placement issue (plus it's two zones simultaneously).

No, I did not assign an address to the keypad when I installed it. But wouldn't that result in an immediate error if there were a conflict? What are the programming sections you're suspecting may be of issue? I think a data conflict seems the most likely.
 
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Old 05-30-19, 11:00 PM
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Ok, so I did a little more investigating and found the following:

I checked the event buffer and found the system was armed at 8:30pm and sounded at 10:50pm on the problem night.

Checking Section [903] revealed only Keypad 1, Keypad 8 (PK5500), the Zone Expander, and Wireless Receiver (from the existing RFK5501). The new keypad and another existing keypad were missing from this list. I reset using [902] and again ran section [903] but nothing changed.

Next, I cleared the EEPROM for my new suspect keypad and re-enrolled all the keypads on partition one as 11, 12, 13, & 18 (the PK5500).

Now Section [903] shows Keypad 1, Keypad 2, Keypad 3, Keypad 8, the Zone Expander, and Wireless Receiver (i.e. everything is there).

To test it, I'm going to use a small piezo in place of the three sirens and see what happens for a couple nights.

Is there anything else I've missed or any other suggestions? More importantly, how would the keypad assignment issue cause an alarm on two door zones? I don't deny the keypads were improperly assigned but don't understand the link to the violated zones.
 
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Old 05-31-19, 02:37 AM
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Check your backup battery. Since the zones are on an expander, and you have a fair amount of devices drawing system power, a little bit of a brownout on an old battery (3-5 years+) could make random zones on the expander glitch like that.
 
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