The design of the multi-channel RS-232C interface standard is a widely used universal standard. It concerns the use of pervasive standards. It covers a wide range, far beyond the fields of communications and computers. In the mid-1960s, the use of switched telephone networks for remote access was almost universal, and the RS-232C interface became more widely used for local communication. This design is based on RS-232 serial port through optical fiber transmission.

With the establishment of distributed computer, the cost of communication equipment for optical end machine has gradually become the main concern of users. In order to reduce these costs, a large number of network structures are studied to determine the use of special equipment as far as possible. Many networks allow geographically distributed users to access common computing devices, building central areas into service centers that link these users to their computers.

Although when terminal traffic is less, using a dedicated leased line charge is not reasonable, but if you can use a lot of common communication terminal equipment structure, general can reduce to the accumulation of a group of users to provide communication cost, and the multiplexer using could use a high-speed line bear turned out to have a set of pulp line transmission business respectively, Therefore, a multiplexer should be considered when a large number of data terminals in the same geographical area communicate, or when many leased lines over arbitrary distances transmit in parallel.