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This article mainly introduces "what is RS232 protocol". In daily operation, I believe many people have doubts about what is RS232 protocol. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the doubts about "what is RS232 protocol"! Next, please follow the editor to study!

What is the RS232 protocol?

RS232 protocol is a popular serial interface used to connect computers to networked devices such as serial port servers. We will learn about the serial port pins used to implement RS232 and some other reference information about the protocol.

The RS232 protocol uses a different signal level than the standard 5V to transmit wire data to minimize signal interference. It performs asynchronous transmission at a constant rate, which is synchronized with the level of the initial pulse signal. The maximum distance of 20 meters is the limit for reliable data transmission using the RS232 interface.

What does RS232 stand for?

Data transmission standards are developed by the Electronic Industry Association (EIA). The prefix RS indicates the recommendation, and all EIA standards begin with these characters. The formal specification of RS232 is that it is an interface that uses serial binary data exchange to communicate between DTE and DCE devices. DTE is the abbreviation of data terminal equipment, while DCE stands for data communication device. The basic example of these two devices defines a computer as a DTE device, while a serial server acts as a DCE.

Serial communication is realized by transferring serial data between DTE and DCE. For example, a computer (DTE) might send binary data "11011101" serially to a serial server (DCE), and then the serial server replies by sending "11010101" back to the DTE device.

The RS232 protocol is used when transferring data between DTE and DCE at specified operating modes, electrical standards, number of bits, and voltage levels.

Serial port server-serial communication equipment

Serial communication equipment uses a 9-pin or 25-pin D connector for cable connection. They are usually specified as DB-9 or DB-25, whose numbers are used to distinguish the number of pins. The names of various manufacturers may replace the DB in the specification. The plug contains sockets and pins, each numbered and marked. The serial pin assignment diagram is shown below.

The RS232 protocol uses a 9-pin serial port, which can have a male or female connector. The latest version of the protocol is called RS232C.

The RS232C retains the functionality of the RS232, but uses 25-pin serial pins instead of 9-pin pins. Whether using a DB9 serial pin output or a 25-pin connection, only three pins are needed to connect the end device.

COM Port Pin arrangement and configuration

RS232 uses the serial pin assignment of DB9 or DB25 to manage traffic between DTE and DCE. These D-sub connectors can be terminated with RS232 or DB25 or DB9 female pins. Each pin in the 9 or 25 serial connector pin arrangement has its own unique function. You can also learn about RS485 pin arrangement.

Function description:

In addition to defining electrical properties, RS232 specifies the signals used for serial cable leads and serial ports. These specifications include familiar items such as timing signals and grounding.

The following is a list of signals used in RS232 COM port pin assignments:

Protective grounding: this signal is connected to the chassis of the metal connector.

Common grounding: the zero reference voltage level of all control signals.

TxD (transfer pin): transfers data from DTE to DCE.

RxD (receive pin): sends data from DCE to DTE.

DTR (data Terminal ready): DTE is ready to accept the request.

DCD (data Carrier Detection): DCE accepts carriers from a DTE located at a remote location.

DSR (dataset ready): DCE is ready to send and receive information.

RI (ring indicator): detects the ringtone of an incoming call on the phone line.

RTS (send request): DCE's DTE call to send data.

RTR (ready to receive): DTE is ready to receive data from DCE.

CTS (clear send): DCE is ready to accept data from DTE.

These signals are the primary RS232 signals, but the protocol also allows secondary signals. They include secondary DTE,RTS,DCD,TxD and RxD. The auxiliary signal is used to optionally connect the DTE and DCE devices.

RS232 empty serial port network converter connection

The serial port server enables serial communication between DTE and DCE devices. The RS232 empty serial port network converter lead connects the Tx pin of the male connector with the Rx pin on the RS232 female head and the Rx male pin to the Tx pin of the female head.

Using the RS232 protocol, you can use a zero serial connection cable to connect two computers that do not have a serial network converter. This highlights one of the original uses of the RS232 protocol, which was developed to enable teletypewriters to communicate with each other through its serial port server.

Straight-through cable

Another type of RS-232 cable is a straight-through cable. It is an one-to-one connector that transmits the pin of one device, which is connected to the transmission pin of another device, and the receiver pin of one device is connected to the receiver pin of another device.

The reason is that RS232 signals travel longer distances. Moreover, it has better anti-noise property. It turns out to be compatible between different manufacturers that connect computers and serial servers.

At this point, the study on "what is the RS232 protocol" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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