Cable Specifications for RS485 Networks – Profibus

The PROFIBUS standard defines two variations of the bus cable. However it is recommended to use cable Type A in all new installations.

Type A is especially recommended for high transmission speeds (>500 kBaud) and permits doubling of the network distance in comparison to Type B.

Technical specification:

Impedance: 35 up to 165 Ohm at frequencies from 3 to 20 Mhz.

Cable capacity: < 30 pF per meter.

Core diameter: > 0,34 mm², corresponds to AWG 22.

Cable type: twisted pair cable. 1×2 or 2×2 or 1×4 lines.

Resistance: < 110 Ohm per km.

Signal attenuation: max. 9 dB over total length of line section.

Shielding: CU shielding braid or shielding braid and shielding foil

Max. Bus length: 200 m at 1500 kbit/s, up to 1,2 km at 93,75 kbit/s. Extendable by repeaters.