The RJ45 interface is usually used for data transmission. The common application is the network card interface, while RS-232, RS-422 and RS-485 are all serial data interface standards. RS-232 is a string that is widely used in PCs and communications. Line interface. RS-232 is defined as a single-ended standard that increases the communication distance in low-speed serial communication. RS-232 adopts unbalanced transmission mode, the so-called single-ended communication.

RS-232 is designed for point-to-point (that is, only a pair of receiving and sending equipment) communication, and its driver load is 3-7kΩ. So RS-232 is suitable for communication between local devices.

422 and RS-485 serial interface standards, RS-422, RS-485 and RS-232 are not the same, the data signal uses differential transmission, also called balanced transmission, it uses a pair of twisted pairs, in the early PC communication More common, RS-422 has a transmission distance of 4000 feet and a transmission rate of 10Mb/s

RS-485 is the same as RS-422, its transmission distance is about 1219 meters, and the transmission rate is 10Mb/s. The length of the balanced twisted pair is inversely proportional to the transmission rate. Only when the rate is below 100kb/s can the specified length of cable be used. Only in a short distance can the rate of transmission be obtained. Generally, the transmission rate of a 100-meter-long twisted pair is only 1Mb/s.

These asynchronous serial communication interfaces are used in computer measurement and control systems. RS232C is a serial bus standard officially issued by the American Electronics Industry Association. It is also a commonly used serial interface standard. It is used to realize the computer and the computer and the peripheral Data communication between. The RS232C serial interface bus is suitable for: the communication distance between devices is not more than 15 meters, and the transmission rate is 20kB/s.