Basic concept of industrial computer serial port:
Serial port, also called COM port. The serial ports on ordinary computers are usually 9-pin, and there are also 25-pin interfaces. Half-duplex RS-485 and full-duplex RS-422 are mostly used on industrial computers. Usually play the role of connecting external equipment and communication.
Generally, there are 6 serial ports outside the motherboard of the industrial computer, and most of them have 10 serial ports and 12 serial ports. For example, Dongtian 4U industrial computer DT-610P-JQ77MA, the motherboard of the industrial computer has 10 serial ports, including 1 RS485 port and 9 RS232 port.
Introduction to serial port types of industrial computer:
If the serial port is divided according to electrical standards and protocols, it can be divided into three types: RS-232, RS-422, and RS485. Next, we will explain one by one.
1. RS-232: It is a serial communication interface commonly used at this stage. It was established in 1970 as a standard for serial communication. The traditional RS-232 interface standard has 22 wires and uses a standard 25-core D-type plug socket. Because RS232 uses 3-15v effective level, the line is a single line, and only two lines can be used to achieve the purpose of full duplex. But the disadvantage is the low transfer rate.
2. RS-422: It is a balanced communication interface, which increases the transmission rate to 10Mb/s on the basis of RS-232, and allows 10 receivers to be connected on a balanced bus. The characteristic is that receiving and sending are separated, so it can receive and send at the same time, that is, full duplex. This is basically the same as the RS-485 circuit principle, which is sent and received in a differential manner, without the need for a digital ground wire.
3. RS485: It has multi-point and two-way communication capabilities, that is, it allows multiple transmitters to be connected to the same bus, and at the same time increases the drive capability and conflict protection characteristics of the transmitters, and expands the common mode range of the bus. It is very convenient for multi-point interconnection and can save many signal lines.
