RS485 communication integrated wiring specification - Solutions - Huaqiang Electronic Network

Single chip microcomputer STM32L151CCU6

SMD aluminum electrolytic capacitor

1206RGB (single)

Photocoupler

Among the many schemes of long-distance communication, RS485 (RS232 to RS485 converter) is reliablely applied between the main control unit, the main control unit and the single-chip microcomputer or peripherals due to its unique electrical performance. To multi-point remote multi-machine communication network to achieve multi-machine response communication. However, the RS485 bus still has defects in anti-jamming, self-adaptation, communication efficiency, etc. The improper handling of some details often leads to communication failures and even system failures. Therefore, improving the stability of the RS485 bus should not be underestimated.

When constructing the 485 bus system, it must be constructed in strict accordance with the construction specifications. In particular, the following points should be noted.
1, 485+ and 485-data lines must be twisted together.
2, the wiring must be clothed with multiple strands of shielded twisted pair. Multi-strand is for standby, shielding is for the convenience of debugging in special situations. Twisting is because 485 communication adopts the principle of differential mode communication, and the anti-interference of twisted pair is better. It is wrong to not use twisted pair.
3, 485 bus must be hand-held bus structure, and resolutely avoid star connection and fork connection.
4. The AC and chassis of the equipment supply must be grounded and grounded. There are many places where there are triangular sockets on the surface. In fact, there is no grounding at all. Good grounding can prevent the equipment from being struck by lightning or surge. When the static electricity is accumulated, the lightning protection design of the device can be used to release the energy better, and the 485 bus device and related chips are protected from damage.
5, in order to avoid strong interference to it, 485 bus should avoid walking with strong electricity.