RS485 cable RS485 communication line RS485 special cable 24 awg shielded twisted-pair cable in general adopt twisted wire can be, but the demand is higher in the environment to the adoption of the belt shielding layer of twisted-pair cable. Using 24 awg shielded twisted-pair cable, for specific transmission line, the host (called test equipment) to the meter 485 between the mouth cable length and data signal transmission of the baud rate is inversely proportional, RS485 cable RS485 communication line RS485 special cable length is mainly affected by the signal distortion and the influence of the noise influence. Theoretically RS485 communication cable transmission distance can reach 1200 meters, but the actual application of transmission distance to less than 1200 meters, and the specific length by the surrounding environment influence.

24 awg shielded twisted-pair cable features: RS - 485 communication cable characteristic impedance for 120 ohm, conductor for 2 * 24 awg stranded tin plated copper wire, PE insulation medium, the aluminum foil/polyester composite with 100% coverage + tin plated copper wire 90% covering a total of 2 layer shielding, with independent grounding conductor, industrial gray PVC outer sheath.

24 awg shielded twisted-pair cable structure:

1) conductor: stranded tin plated copper wire, or seven branch, each conductor wire diameter is 0.30 mm, four strands of conductor, outside diameter: 0.91 + / - 0.03 mm

2) insulation: solid core PE insulation, outside diameter: 1.90 + / - 0.03 mm

3) the first screening: aluminum foil shield

4) drainage line: stranded tin plated copper wire, or seven branch, each conductor wire diameter is 0.30 mm, a total of one share, outside diameter: 0.91 + / - 0.03 mm

5) the second shield: aluminum magnesium mesh grid shielding, coverage is 55%

6) inner sheath: black PVC, OD: 8.0 mm + / - 10%

According to the test, RS485 communication cable's largest communication distance is about 1219 m, the biggest transmission rate for 10 MB/S, transmission rate and transmission distance is inversely proportional, in 100 KB/S transmission rate, to achieve the maximum communication distance, if need more long transmission distance, need to add 485 repeater. RS485 bus general maximum support 32 nodes, if use special 485 chip, can achieve 128 or 256 node, the biggest can support to 400 nodes.

Because of RS485 interface has good resistance to noise interference resistance, long transmission distance and standing ability the above advantages will make it be the first choice of the serial interface. Because RS485 interface composed of half duplex network, typically require two root attachment, so RS485 interface are used shielded twisted-pair cable transmission.