RS485 and RS232: two major differences in the communications industry

RS485 communication is a widely used communication standard and plays an important role in many fields. It adopts a differential signal transmission method and has the characteristics of long transmission distance, strong anti-interference and high-speed data transmission.

In RS485 communication, data transmission is carried out through a pair of wires, one wire pair is responsible for sending data, and the other wire pair is responsible for receiving data. Because of the differential signal transmission method, it effectively resists external interference, thus ensuring the stability and reliability of data transmission.

As a common industrial communication protocol, the RS485 bus has been widely used in industrial automation, smart home, smart transportation and other fields. Next, we will explore some major RS485 application scenarios:

1. Industrial automation: In the field of industrial automation, the RS485 bus is widely used for communication and control between devices. It realizes data transmission and remote control between devices through the RS485 bus, thereby significantly improving production efficiency and product quality.

2. Smart home: RS485 bus is also widely used in the field of smart home. Using the RS485 bus, various types of smart devices are interconnected, including functions such as remote control and voice control, which greatly improves the convenience and comfort of family life.

3. Intelligent transportation: The RS485 bus is also widely used in the field of intelligent transportation for communication and control of traffic lights, surveillance cameras and other equipment. The RS485 bus helps realize remote monitoring and management of traffic equipment, greatly improving the efficiency and safety of traffic management.

Relatively speaking, RS232 communication is another common serial communication interface standard, mainly used for communication between computers and other devices. RS232 uses level conversion to convert TTL levels (0~"<0.8v", 1~">2.0V") into RS232 levels (-15V to -3V is logic "1", +3V to +15V is logic "0") for connection with TTL circuits.

RS232 typically uses a 9-pin (DB-9) or 25-pin (DB-25) connector. It has the characteristics of short transmission distance, low transmission rate, and weak anti-interference ability.

Below we will discuss some of the main RS232 applications:

1. Communication between computers and external devices: The RS232 interface is commonly used for communication between computers and external devices such as printers, modems, monitors, and terminal equipment. Through the serial port connection, two-way transmission of data can be achieved, so that external devices can interact with the computer.

2. System debugging and control: RS232 serial port is often used for system debugging and control. By connecting the computer and debugging tools or control equipment through the serial port, system debugging, monitoring and control operations can be performed, such as controlling embedded systems, debugging hardware equipment, etc.

3. Data acquisition and monitoring: The RS232 serial port can also be used for data acquisition and monitoring applications. Connect sensors, measuring instruments or other data collection equipment through the serial port, and transmit the collected data to a computer or data recording device for subsequent data processing and analysis.

4. Remote control and remote access: The RS232 serial port can also be used for remote control and remote access. By connecting remote devices such as switches, routers, etc. through the serial port, configuration, monitoring and management operations can be performed to achieve remote control and access.

There are significant differences between RS485 communication and RS232 interface in many aspects:

1. Transmission method: RS232 uses unbalanced transmission, that is, single-ended communication, while RS485 uses balanced transmission, that is, differential transmission.

2. Transmission distance: RS232 is suitable for local device communication. The transmission distance usually does not exceed 20 meters, while the transmission distance of RS485 can reach tens of meters or even thousands of meters.

3. Connection method: RS232 usually uses three wires: a sending wire, a receiving wire, and a ground wire. On the contrary, RS485 generally uses a two-wire system for transmission, including two transmission lines A and B.

4. Level signal: The logic 1 of RS232 is -3V to -15V, and the logic 0 is +3V to +15V. In comparison, RS485's logic 0 is -2V to -6V, logic 1 is +2V to +6V, and the voltage is the voltage between line A and line B.

5. Transmission rate: RS232 has a lower transmission rate, with a maximum baud rate of 19200bps, while RS485 has a higher transmission rate, up to 10Mbps.

To sum up, RS485 communication and RS232 interface each have unique characteristics and applicable fields. RS485 communication uses differential signal transmission and is widely used in industrial automation, smart home and other fields, while RS232 interface uses level conversion and is mainly used for communication between computers and other devices.