Electronics Industry Association (Reference: USA, org.)

Electronics Industry Association

<standard> (RS) A series of EIA standards including EIA-232. (1995-03-28)

The Electronic Industries Alliance (EIA; until 1997 Electronic Industries Association) was an American standards and trade organization composed as an alliance of trade associations for electronics manufacturers in the United States. They developed standards to ensure the equipment of different manufacturers was compatible and interchangeable.

<communications, standard> (Formerly "RS-449") An EIA standard for a 37-pin or 9-pin D-type connector (functional- and mechanical characteristics), usually used with EIA-422 or EIA-423 electrical specifications. (2002-10-05)

<communications, standard> (Formerly "RS-232") The most common asynchronous serial line standard. EIA-232 is the EIA equivalent of ITU-T V.24, and V.28. EIA-232 specifies the gender and pin use of connectors, but not their physical type. RS-423 specifies the electrical signals. 25-way D-type connectors are common but often only three wires are connected - one ground (pin 7) and one for data in each direction. The other pins are primarily related to hardware handshaking between sender and receiver and to carrier detection on modems, inoperative circuits, busy conditions etc. The standard classifies equipment as either {Data Communications Equipment} (DCE) or Data Terminal Equipment (DTE). DTE receives data on pin 3 and transmits on pin 2 (TD). A DCE EIA-232 interface has a female connector. DCE receives data from DTE on pin 2 (TD) and sends that data out the analog line. Data received from the analog line is sent by the DCE on pin 3(RD). Originally DCE was a modem and DTE was a computer or terminal. The terminal or computer was connected (via EIA-232) to two modems, which were connected via a telephone line. The above arrangement allows a computer or terminal to be connected to a modem with a straight-through (2-2, 3-3) cable. It is common, however, to find equipment with the wrong sex connector or with pins two and three reversed, requiring the insertion of a cable or adaptor wired as a gender mender or null modem. Such an adaptor is also required when connecting a computer directly to a terminal or to another computer without the use of modems. (1999-12-28)

<communications, standard> (Formerly "RS-485") An EIA serial line standard which specifies 2-wire, half-duplex, differential line, multi-point communications. Maximum cable length is 1200m. Maximum data rates are 10Mbps at 1.2m or 100Kbps at 1200m. EIA-485 can implement a truly multi-point communications network, and specifies up to 32 drivers and 32 receivers on a single (2-wire) bus. Differential SCSI uses EIA-485. {Details on RS-232, 422, 423, and 485 (http://rs485.com/rs485spec.html)}. (2003-04-18)

<communications, standard> (Formerly "RS-423") An EIA serial line standard which specifies single ended communication. The mechanical connections for this interface are specified by EIA-449. Although it was originally intented as a successor of EIA-232 it is not widely used. The EIA-232 standard has its limits at 20kbps and 1.5m. EIA-423 can have a cable lenght of 1200m, and achieve a data rate of 100Kbps. When no data is being transmitted, the serial line is at a logical zero (+3 to +15 Volts). A logical one is represented as a signal level of -15 to -3 Volts. In practise, one often finds signals which switch between nominally +4.5 and +0.5 Volts. Such signals are large by modern standards, and because the impedance of the circuits is relatively high, the allowable bit rate is modest. The data is preceded by a start bit which is always a logical one. There may be seven or eight bits of data, possibly followed by an even or odd parity bit and one or two stop bits. A "break" condition is a continuous logical one on the line which is what would be observed if nothing was connected. {Comparing EIA-422, 423, 449 to RS-232-C (http://rad.com/networks/1995/rs232/rs449.htm)}. {Details on RS-232, 422, 423 and 485 (http://rs485.com/rs485spec.html)}. (2002-10-05)

EIA-449

The RS-449 specification, also known as EIA-449 or TIA-449, defines the functional and mechanical characteristics of the interface between data terminal equipment, typically a computer, and data communications equipment, typically a modem or terminal server. The full title of the standard is EIA-449 General Purpose 37-Position and 9-Position Interface for Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange.