RS-232

Definition

RS-232 is a serial interface published by the EIA for asynchronous data communication over distances up to a few hundred feet.

Characterized by a single-ended (not differential) physical layer, it uses one signal wire for transmission, another for reception, and a common wire (ground), plus some timing and control signals. Its specifications are rooted in electromechanical equipment signaling (Teletype machines). Still a very common interface but largely replaced by USB in recent years.

The term "serial" interface is often used for an RS-232 interface. The usage is not quite accurate—while RS-232 is a serial interface, there are other serial interfaces in addition to RS-232.

When it was introduced in 1987, the MAX232 rapidly became the most common way to implement RS-232 because it required only a single 5-volt supply. On-board DC-DC converters developed the odd voltages required by the official spec. Maxim still manufacturers the MAX232 and makes a wide range of newer products as well.

Synonyms