Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!decvax!tektronix!ogcvax!omsvax!icalqa!hplabs!sri-unix!vonglahn%udel-eecis1.udeecis@udel-ee.arpa From: vonglahn%udel-eecis1.udeecis@udel-ee.arpa Newsgroups: net.micro Subject: Re: Rs-449, -422 -423 Message-ID: <12721@sri-arpa.UUCP> Date: Mon, 17-Oct-83 13:30:13 EDT Article-I.D.: sri-arpa.12721 Posted: Mon Oct 17 13:30:13 1983 Date-Received: Sun, 23-Oct-83 07:16:01 EDT Lines: 31 From: vonglahn Interface standards the physical (connector type, pin assignment, signal name) and the electrical (voltage levels, signal definitions, timing relationships, etc) characteristics of an interface between two pieces of equipment. The three standards mentioned were developed by the Electiral Industry Association (EIA) as a follow-on to the RS-232 specification. They address the interface between Data Terminal Equipment (e.g. VDT) and Data Communication Equipment (e.g. modems). Specifically: RS-422 specifies the electrical characteristics of a BALANCED interface connection usable for speeds of 10 Mbps @ 40 feet. (Balanced interfaces use two active lines per signal and have better performance in noisy environments). RS-423 specifies the electrical characteristics of an UNBALANCED interface connection similar to RS-232. (Unbalanced interfaces use one active line per signal.) It is specified for a maximum speed of 100 Kbps @ 40 feet. RS-449 specifies the functional and mechanical characteristics of the RS-422/3 interfaces. It deals with such things as connector type, circuit names, circuit functions, connector pin assignment, and when to use -422 or -423 (requires the use of RS-422 circuits for speeds above 20 Kbps, for example). Hope this helps some. Pete (vonglahn%udel-ee.ARPA)