<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. Details on RS-232, 422,
423 and 485.
EIA-232 « EIA-232C « EIA-422 « EIA-423 »
EIA-449 » EIA-485 » EIA-530