130522-0759 EDT
ucdoshi:
I am working on the development of a binary voltage presence detector. This interfaces to a "1-wire" bus, and in turn that can interface to an RS-485 bus. This is not yet available and I am not trying to sell it to you. The purpose of this comment is to describe the system.
What do I mean by "binary voltage detection"? This is a voltage sensing device that has two states defined by a threshold voltage. An ordinary relay, optical coupler, vacuum tube, or transistor can all be used to perform this input detection.
By using a single bus system with addressable sensors one can have many sensors and a simple wiring scheme.
At the master end of the bus there can a rather complex analysis program with a simple output display.
The 1-wire network is useful up to 100 ft or so. This is not a high noise immunity bus. RS-485 is usable to 4000 ft at 115.2 kbaud, and 8000 ft at 9600 baud. The "1-wire" name is a registered trademark of Dallas Semiconductor now part of MAXIM.
The device I am working on is intended for monitoring residential furnace blower and thermostat signals, and industrial machine conditions like pallet present, blocked and starved conditions, and other station signals. In addition to voltage sensing other sensors like temperature and current can be on the same "1-wire" bus.
For your application look for an addressable bus system, and possibly RF communication between the buildings.
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