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The difference between RS-232 serial port and RS-485 serial port

The difference between RS-232 serial port and RS-485 serial port


The RS232 serial port is the most widely used serial port type in the computer and communication industries.

The system adopts full-duplex system and requires three lines: ground line, sending line and receiving line, only RS232 can realize point-to-point communication


Disadvantages of RS232 serial port :


The level value of the interface signal is high, which is easy to damage the interface circuit chip. Because of the incompatibility with the TTL level, all the level conversion circuit can be used to connect with the TTL circuit.

Poor anti-interference ability

Limited transmission distance, usually within 15 meters

Only point-to-point communication is possible

The transmission rate is lower, in the case of asynchronous transmission, the baud rate is 20Kbps


RS485 serial port advantages :


RS485 adopts balanced transmission and differential reception, which has good anti-interference ability, and the signal can reach more than 1000 kilometers.


RS485 has two-wire line and four-wire line. Under the four-wire system, only point-to-multipoint communication can be achieved (that is, there is only one master device, and the rest are slave devices).


At present, there are few applications of the four-wire system, and the two-wire system is mostly used for wiring.

Two-wire RS485 can only use half-dual mode, and cannot send and receive emails at the same time.


On the same bus, RS485 can connect up to 32 nodes to realize multi-point communication in the true sense, but it usually adopts master-slave communication, that is, a host with multiple nodes at the same time


The RS485 interface has the advantages of strong anti-interference ability, long transmission distance and strong multi-station capability, and has become the preferred serial interface.

High transmission rate, the highest transmission rate can reach 10Mbps


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