Addressable Devices? (Fire Alarm)

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Thread Starter


Joined Feb 19, 2011
Hello, I know there are a few fire alarm fanatics here and maybe some that even designed a fire alarm panel for a manufacturer. I'm in the process of designing a FACP and I've wired all my connections up and I'm using a PIC18F4550 as the brains. Here are my specs:

24v, 2 zone, 2 C Form Relays, 2 NACs, LCD Display

As you may guest I'm building it with all the bells and whistles kinda like the Silent Knight 5600. I'm able to figure out how to do everything such as determining if someone has cut the wires, having the relays switch during a event, etc...

One thing still makes my head scratch is how does the panel know which 4 wire smoke detector has went off? I know the SLC is used for the communication, but does the smoke detector output a ID or a address number in binary code when it's detected a fire?

If someone can break down how this process is done, that would be great! Because if I can get my panel get a address of pull station or a SK detector that would be great!

Thanks, Andrew.
heyy guys..i have made small circuit fire alarm which works on 10 volt battery..der is diode sensor which sense the match stick heat n speker produces sound... so i want led light n motor fan should get off when this fire alarm senses the der any idea how i can do this ..pls reply asap


Joined Jun 22, 2012
Addressable fire alarm systems use 2 wires as the signalling loop, and poll each device evey 5seconds to see what its status is, like fire or fault, they also have sounders on the loops as well,they generally use I2C protcol to send/receive data, superimposed on a 24V supply.
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