This can extend the reader length to about 10 meters. Please refer to Bulletin xxxx for a full description on this topic. For DC circuits, use a 3A diode, such as 1N5403 as surge suppressor. The surge suppressor should always be installed as near to the inductive load as possible. RS422 data cable such as Normal 4-core telephone cables work well as communication cable.
Shielding is normally unnecessary.
The more important factor for limit interference is twisting the cable pairs. For outdoor, use jelly-filled telephone cable to prevent water from entering the cable. When ever bus lines run across open spaces, you must take into consideration of lightning problem and design into the bus lightning arrestors, and good earthing.