A simple rs232 to rs485 converter circuit design
The rs232 to rs485 converter manufacturer tells you that RS-232, RS-422 and RS-485 are all serial data interface standards, which were originally formulated and issued by the Electronic Industries Association (EIA). RS-232 was released in 1962 and named EIA-232-E as an industrial standard to ensure compatibility between products from different manufacturers. The manufacturer of rs232 to rs485 converter tells you that the maximum transmission distance is about 15 meters, the maximum rate is 20kb/s, and RS-232 is designed for point-to-point (that is, only a pair of receiving and sending devices) communication. Therefore, RS232 is only suitable for local communication.
The manufacturer of rs232 to rs485 converter tells you that RS-422 is developed from RS-232, and it is proposed to make up for the shortcomings of RS-232. In order to improve the shortcomings of RS-232 communication distance and low rate, RS-422 defines a balanced communication interface, which increases the transmission rate to 10Mb/s and the transmission distance to 1200 meters (when the rate is lower than 100kb/s), And allows up to 10 receivers to be connected on a balanced bus. RS-422 is a unidirectional, balanced transmission specification for single machine sending and multiple machine receiving, and it is named TIA/EIA-422-A standard.
The manufacturer of rs232 to rs485 converter tells you that in order to expand the scope of application, EIA formulated the RS-485 standard on the basis of RS-422 in 1983, adding multi-point and two-way communication capabilities, that is, allowing multiple transmitters to be connected to the same bus. On the above, the drive capability and conflict protection features of the transmitter were increased at the same time, and the common mode range of the bus was expanded, and it was later named the TIA/EIA-485-A standard. The manufacturer of rs232 to rs485 converter tells you that the recommended standards proposed by EIA are all prefixed with RS, so in the field of communication industry, it is still used to refer to the above-mentioned standards as prefixes with RS. The rs232 to rs485 converter manufacturer tells you that RS-232, RS-422 and RS-485 standards only stipulate the electrical characteristics of the interface, and do not involve connectors, cables or protocols. On this basis, users can establish their own high-level communications protocol.