Dce (data communication equipment or data circuit terminal equipment): This equipment and its connection with the communication network constitute the user network interface of the network terminal. It provides a physical connection to the network, forwards traffic, and provides a clock signal to synchronize data transmission between dce devices and dte devices. Modems and interface cards are examples of dce devices.

Dte (data terminal equipment) refers to the equipment located at the user network interface, which can be used as a source, a sink, or both. A data terminal device is connected to a data network through a data communication device (e.g., a modem), and usually uses a clock signal generated by the data communication device. Data terminal equipment includes computer, protocol converter and demultiplexer.

The standard characteristics of the interface between dte and dce are mechanical, electrical, functional and procedural. The mechanical characteristics specify the actual physical connection details of dce and dte. The electrical characteristics stipulate the codes that dte and dce must use, the same voltage must be used to describe the same state, and the signal bits with the same width must be used. These characteristics determine the data transmission rate and distance that can be achieved. The functional characteristics specify the functions to be completed by each switching circuit. According to the functional characteristics of the interface, the process characteristics specify the sequence of events to transmit data.

On the one hand, dce is responsible for sending and receiving bits on the transmission medium or network, one bit at a time. On the other hand, dce must interact with dte. Generally speaking, this requires the exchange of data and control information, which is done through a set of switched circuit lines. In order to operate this mechanism, two DCEs that exchange signals on transmission lines or networks must understand each other. In addition, each dte-dce pair must be designed to cooperate and interact. In order to reduce the burden of data processing equipment manufacturers and users, communication interface standards are stipulated.

Rs-232 interface is the interface between dte (data terminal equipment) and dce (data communication equipment). Dte includes computers, terminals, serial printers and other devices. Usually only the com port of modems and some switches is Dce. The standard indicates that dte should have a plug (pin output) and dce should have a socket (hole output). This point is often ignored by manufacturers, but it has little impact.