The sensor is capable of RS-485, both half and full-duplex, and I have used that before. The sensor board (0.25" wide X 1.9" long) has stuffing options that allow all sorts of protocols - I2C,RS232,RS-485.

I have 8 or 10 different "Main" (or controller boards) already designed, any one of which that could control the sensor array. The particular feature set the customer wants, (SSH, SNMP, telnet, Real-Time Clock, Large event log) is on a board that doesn' t have an RS-485 chip. I don't want to design a new add on board at this time, so I'm going with the single-ended stuff. The customer will be using 30 sensors on 400' (total) of 4-wire cable. I think it will work!