Because RS485 shielded twisted pair cable interface has good anti-noise interference, long transmission distance and multi-station capability, it becomes the preferred serial interface. Because the half-duplex network consisting of RS485 interface only needs two connections, RS485 interface adopts shielded twisted pair transmission.
RS485 shielded twisted pair cable structure:
1. Conductor: multi-strand tin-plated copper strand and conductor. The conductor surface is free of oil and dust. Conductor DC resistance should conform to the standard.
2. Insulation: Extruded with ordinary PVC insulating material, the insulating surface should be smooth and round, and there should be no natural shrinkage. The diameter of insulating core should be strictly produced according to this process, and the color separation of insulating core should be based on customer needs.
3. To twist the insulated cores and make them into cables, the outer diameter of the cables should be rounded, the pitches should be uniform and uniform, and the cores should be wrapped tightly by overlapping polyester tapes.
4. Adding 7/0.15 tin-plated wire as drainage ground wire, and then adding aluminium-plastic composite tape to cover.
5. Braiding: Tin-plated braiding shield with shielding density of 80%. The braiding layer should be smooth, burr-free, leak-free and oil-free.
6. Sheath: The sheath is extruded with ordinary purple PVC sheath material. The surface of the sheath is smooth and round.

RS485 shielded twisted pair cable technical parameter