DSC 832, smoke and why PGM


  #1  
Old 05-26-05, 08:09 AM
FatFish
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DSC 832, smoke and why PGM

Hi,
I've hard time understanding why I must use the pgm for the smoke detector.
I did a search but found nothing related to pgm and smoke detector.

All I want to do is to have my 3 smoke detectors on a different zone.

The installer guide says to use AUX + and PGM2 and I can't really understand why.

Can someone explain? I'll probably say of course ...

Also since I want each one to be on a zone:
I'll have to have each one terminated with a resistor and a relay and have each one connected in parallel on AUX+ and PGM2.
Is that rigth?

The user guide also says to use 18 gauge wire but my last appartement the smoke detector was wire using regular 4-wire phone cable (gauge 22).
Is it only for the power?

Thanks.

Nick
 
  #2  
Old 05-26-05, 04:45 PM
S
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first off are your smokes 2 or 4 wire? you use the program and aux so that you can use the relay to reset (drop power to them) incase of alarm.
if they are 4 wire the power wires go to aux and pgm the loop wires to one of the zones. if they are 2 wire you just hook them to the aux and pgm. if they are 2 wire there is a jumper on board marked con 1 this needs to be removed if they are 4 wire leave it on the pins. answer these questions then we'll know how to program
 
  #3  
Old 05-28-05, 12:28 PM
FatFish
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sorry about the missing info.

4-wire smoke.

From what I've understood, PGM when set for smoke (4-wire) is the return path (ground) for the power loop.
It seems to be for the RESET or * 7 4
When RESET is done the PGM is lift cutting power to the smoke.
The relay then close I guess to have the end of line resistor in the loop for the sensor part (that is now back to open with the power loss).

Why do you need a relay at all in fact? Why not jsut put the resistor at the end?

The doc says Power Supervisory Relay (DCS RM-1)... is there a substitute for that? It looks like an ordinary relay.

Thanks.
 
  #4  
Old 05-28-05, 06:44 PM
S
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The purpose of the eol relay is to supervise the power to the smoke if it loses power it will open the loop side and cause a fire trouble. Could you just put a resister on the loop, yes ,is it correct no. the smoke could lose power and you would never know it. 2nd question yes you could use any 12 volt relay for this. A relay that is designed for this purpose is compact and usually heat shrunk to prevent any shorts,grounds or the relay falling out. But no you do not have to use the dsc spec relay unless you are looking to meet ul as dsc designed it and had it approved.
 
  #5  
Old 05-28-05, 09:23 PM
FatFish
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oh I see!
The relay is acting as a "Normally Closed" contact with the Smoke (normally open) and in case of malfunction at the smoke level it will trig the contact and the system will know it's a failure.

oups I checked the PC5010 user guide and the relay is picture as a normally open contact like this " = ".


Am I missing something again?
 
  #6  
Old 05-29-05, 03:26 AM
S
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you've basically got it. the relay is closed when power is applied to it if it loses power it opens. So when wired with one leg of your fire loop to relay comman and the other relay leg to your smoke with resistor across the terminals on smoke det. if a power problem to smoke occurs it will open the fire zone causing a trouble. dont twist the resistor and loop wires together so if a wire comes off of terminal it will open the loop also.
 
  #7  
Old 05-29-05, 02:45 PM
FatFish
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Thanks Steve!
This subject (4-wire smoke) really need to be part of a FAQ or a sticky of some sort. I'm sure that everyone is kind of having some trouble or are juste wiring without power supervision.
Beside the smoke detector, I was able to wire and program with LCD keyboard without too much problem. (I'll try the PC link, I found the pinout and soft)

Last question if you have patience ...
I just saw some picture of a relay on a PCB and there is a diode, probably between the + and -
Is it really necessary and what kind of diode?

Thanks again.

Edit:
ok found the answer myself. The diode is there to protect against the brief high voltage 'spike' produced when the relay coil is switched off.
A simple 1N4148 should do.
 

Last edited by FatFish; 05-30-05 at 06:52 AM.
  #8  
Old 05-30-05, 10:30 AM
M
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That's not a bad suggestion. I'm always looking for good subjects to add to the FAQ. It's one of those "blind spot" kind of things. When you work with this technology on a regular basis, you sometimes miss seeing how complicated a concept can be without having the background.
 
 

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