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how Addressable Systems works?

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me_guitarist

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Can anyone explain how a Fire Alarm Addressable systems works?
& what is loop powered?

I'm thinking of design some addressable devices for Addressable Fire Alarm Systems but don't know where to start with.

As I know it use only 2 wire to connecting devices & communicate with each other with a specific protocol. But how can this 2 wires supply power to PICs & transmit/receive data?

I search around the web but couldn't get any info for this.
Hopefully somebody can point me the right directions.

Thanks in advance!
 

Re: Fire Alarm Addressable Systems

I think it is called loop power simply because it loops from one device to the next?
A control panel can have more than one loop controlling different zones.
The data is modulated onto the positive rail as negative going square pulses to about half the supply voltage. So if it was a 12 volt system, the amplitude of the data would be ~ -6V.
Each device on the loop has a voltage regulator and filter to provide a stable supply to the micro. The positive line is capacitor coupled to a Schmitt type trigger circuit to recover and clean up the data. Each device in the loop has a DIL switch to set up a unique address.
The data is similar to RS232 in format with the control panel being the master.
I do not know if there is a standard protocol.
 

Re: Fire Alarm Addressable Systems

btbass said:
I think it is called loop power simply because it loops from one device to the next?
A control panel can have more than one loop controlling different zones.
The data is modulated onto the positive rail as negative going square pulses to about half the supply voltage. So if it was a 12 volt system, the amplitude of the data would be ~ -6V.
Each device on the loop has a voltage regulator and filter to provide a stable supply to the micro. The positive line is capacitor coupled to a Schmitt type trigger circuit to recover and clean up the data. Each device in the loop has a DIL switch to set up a unique address.
The data is similar to RS232 in format with the control panel being the master.
I do not know if there is a standard protocol.
Click to expand...

Hi btbass,
Thanks for yr reply.

how can we modulate the data onto the positive rail?
like a RS232, it need 2 power & 2 data line to communicate right?

Added after 1 minutes:
 

Fire Alarm Addressable Systems

Hi me_guitarist,
You must apply a serial bit-srteam trough higher load/change current in your loop...
K.
 

Re: Fire Alarm Addressable Systems

No, you just use two power lines. The data is sent through the power lines.
There are many ways to modulate the power supply.
There are also systems that use tone signaling modulated onto the power supply lines.
 

Re: Fire Alarm Addressable Systems

btbass said:
No, you just use two power lines. The data is sent through the power lines.
There are many ways to modulate the power supply.
There are also systems that use tone signaling modulated onto the power supply lines.
Click to expand...

Thanks btbass.

If I'm using PICs what features do i need?
Any example or info I can learn from?
 

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