Elk Rule to un-latch smoke detector

[scotsman]

I am trying to put together a small alarm system in my back house (Area 2) driven by a ELK-P212S Supervised Remote Power Supply that is connected via a long cable to my Elk M1 in the main house (Area 1).
 
There's a 4-wire smoke detector in the back house connected via a relay driven by the output of a keypad (output 197) to unlatch after an alarm state.

What is the right rule to unlatch the smoke alarm after you enter the code on the keypad the second time?
 
So far I have:
 
WHENEVER Area 2 Arm State becomes disarmed 
 
   THEN turn Output 197 ON FOR 2 SECS
 
 
Anyone help?? Thanks!

 

[Del91574]

Not a good idea.
 
You should drive the output via the normal switched power for reset.
 
The way you're aiming for will generate a trouble condition assuming you have it wired correctly with a power supervisory relay.....each cycle would generate a trouble condition.

 

[scotsman]

Hmmm no idea how I can reach the back house with the SAux from the M1. Yes it does have a relay.

Not sure if I fully understand your advice. Surely all the SAux does is allow a temporary power disruption to unlatch from the smoke's alarm state? Surely this is equally possible with a relay connected across the 12V power to the smoke? Or am I missing something very obvious?

 

[RAL]

Hmmm no idea how I can reach the back house with the SAux from the M1. Yes it does have a relay.

Not sure if I fully understand your advice. Surely all the SAux does is allow a temporary power disruption to unlatch from the smoke's alarm state? Surely this is equally possible with a relay connected across the 12V power to the smoke? Or am I missing something very obvious?

 
Yes, you can use a relay to reset the power to the smokes in the back house.  The question is what is controlling that relay.  DEL's point is that the relay should be powered by SAUX.   SAUX drops power momentarily as part of the SMOKE RESET issued from the keypad.  If you drop power to the smokes at any other time, then that will result in a trouble condition on the M1.

 

[scotsman]

OK I get it. Thanks! I was going to use the built in output relay on the elk P212S supervised remote power supply, following the manual:

Output "B" Functionality:
The local "Output B" relay is free to be used as a programmable output when the P212S is used in M1 mode. In other words, in the M1 mode this relay does not represent or follow the Low Battery or Battery condition. It can be used by the M1 Rules Programming for nearly any application imaginable. Some examples of its use are:

- For resetting (breaking) power to a latching detector. This can easily be done by series wiring either the POS or NEG power lead powering the detector through the contacts of Output B.

So any way around the trouble condition on the M1 this would create?

 

[RAL]

OK I get it. Thanks! I was going to use the built in output relay on the elk P212S supervised remote power supply, following the manual:

Output "B" Functionality:
The local "Output B" relay is free to be used as a programmable output when the P212S is used in M1 mode. In other words, in the M1 mode this relay does not represent or follow the Low Battery or Battery condition. It can be used by the M1 Rules Programming for nearly any application imaginable. Some examples of its use are:

- For resetting (breaking) power to a latching detector. This can easily be done by series wiring either the POS or NEG power lead powering the detector through the contacts of Output B.

So any way around the trouble condition on the M1 this would create?

 
Although the P212S manual says that Output B can be used to reset latching detectors, I guess I'd have to say that that doesn't apply to smoke detectors.
 
Smokes need to be reset in a coordinated manner with the alarm panel. The panel needs to know that the smokes are going to lose power and that the trouble condition that results should be ignored.  That's why there is the special "smoke reset" command on the M1. 
 
I can't think of a way to reset the smokes that won't cause a trouble condition that doesn't use SAUX in some manner. 
 
Unfortunately, the M1 doesn't have a rule that would allow you to write something along the lines of
 
Whenever SAUX turns off,
Then turn on Output xxx (Output B)
 
A kludgy way to accomplish this would be to connect a relay to SAUX back at the M1, and then connect the relay contacts to a spare zone input on the M1.  Then write rules along the lines of
 
Whenever Zone xxx becomes secure    (zone xxx is connected to the SAUX relay)
Then Turn Output yyy On    (yyy is Output B)
Whenever Zone xxx becomes not secure   
Then Turn Output yyy Off
 
I'm not sure this would really work, as delays in the processing of the rules might prevent the power interruption to the smokes from overlapping exactly with the interruption in SAUX power.
 
Another thought is that since you have a Cat5 cable to the back house that connects to the zone expander, you might try using the spare conductors in the cable to carry SAUX out there and drive a 924 relay to cut power to the smokes. 

 

[scotsman]

Thanks for the response! Very helpful. Unfortunately no spare wires in the cat5 cable. I might try your relay idea and see if it works. I’ll report back...

 

[RAL]

Thanks for the response! Very helpful. Unfortunately no spare wires in the cat5 cable. I might try your relay idea and see if it works. I’ll report back...

 
Are you already using the spare Cat5 pairs for something else?  You really only need one additional conductor for SAUX since the 4 wires that make up the data bus already provide a signal ground (NEG) wire.  If you power the back house keypad and zone expander from the P212S, you could re-purpose the +12V wire for use as SAUX.

 

[Del91574]

Only need a single conductor to drive a TTL relay.