GB/T 12057-1989

This standard specifies the mechanical and electrical characteristics for 37-position and 9-position interface connectors used between data terminal equipment (DTE) and data circuit-terminating equipment (DCE) in serial binary data interchange systems. It is applied in telecommunications and computing environments to ensure physical compatibility and signal integrity for devices such as modems, terminals, and multiplexers operating with serial data transmission. The standard defines pin assignments and interface circuit functions, facilitating interoperability in industrial, commercial, and testing contexts where reliable data exchange is required.