(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).
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-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. […]
communications, standard (Formerly “RS-530”) An EIA serial line standard which specifies differential line and singe ended communications. Combining EIA-422 and EIA-423, and defining a 25-pin connector for mechanical connections, this standard serves as a complement to EIA-232 for high(er) speed data transmissions. (2002-10-05)
abbreviation 1. European Investment Bank European Investment Bank