I need to construct a network of sensors. Because of limitations they MUST be wired. This means NO WiFi, ZigBee, bluetooth, or other rf/ wireless networking protocols. What I need to do is to transmit power to each sensor, and when triggered above a preset level, the sensors send their address code and the voltage value. I'm thinking there will not need to be more than 8 bits of data in either the address or voltage. I assume the data will need to be sent serially. What's the best way to do this? Can someone point me to a reference (preferably on-line)? How do I avoid packet collision? Are there alternatives to doing data transmission synchronously to avoid this? There is no need for high speed/high data rate transmission, but what's the highest rate I can get over twisted pair? Is there a reference somewhere that shows data rates vs distance? And lastly, what is the minimum number of wires I could use, assuming I use twisted pair of suffecient gauge so there's not a voltage drop (phantom powering?)?
12 years ago