What kind of cable should I use for RS-485 communications?

A good economical solution for field wiring is to use CAT5 or CAT6 twisted pair cable. Connect each twisted pair to the same set of signal pins – TX+/TX- would be one pair of conductors, RX+/RX- another pair of conductors, and GND a third pair of conductors. This helps to cancel out noise or voltage differences that are induced or radiated into untwisted cables. To easily terminate twisted pair field wiring, use the Sealevel TBRJ45 terminal block with an RJ45 connector to screw terminals.