Anybody worked with Polling Loop Technology

Hi,

I need to know the details of polling loop technology used in some fire alarms and burglar alarm. It is patented by honeywell. I am planning to use a two wire data and power interface to support a multidrop network of switches over a long distance (10kms). I have already implemented my own multiplexed switching circuitry with a PIC18F452 as a master and PIC16F676s as multiple slave. It is an adaptation of power line modulation. But I want to make it more robust.

The basic purpose is a large number (upto 255) of sensors (activated by a switch) on a two wire bus connected to the master. My scheme right now has latency issues of activation detection. Cannot use a CAN type scheme due to power and length limitations. A baudrate of 110B okay. A total lenght of upto 10KM.

Any suggestion is most welcome.

Regards

Sougata