Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!apple!uokmax!slfields From: slfields@uokmax.ecn.uoknor.edu (Scott L Fields) Newsgroups: comp.sys.next Subject: Re: RS423 - RS232 line levels (volts) different Message-ID: <1990Dec31.170055.8728@uokmax.ecn.uoknor.edu> Date: 31 Dec 90 17:00:55 GMT References: Organization: Engineering Computer Network, University of Oklahoma, Norman, OK Lines: 18 In article lclarke@questor.wimsey.bc.ca (Lawrence Clarke) writes: >The Network Administrator's guide tells you how to convert a from the new >NeXTstation's RS423 serial port to an RS232 port. But they forgot to >mention that the RS423 uses +- 5 volts and an RS232 uses +- 12 volts. >I have some equipment that was built to RS232 specs and will not work with >the NeXTstation. Some of the newer modem's out there will work though, as >most of them were not built to RS232 specs. There's more than just a pinout >difference between the 2 standards (RS423 - RS232). I would think that there would be few devices out there would fail to work on that merit. The usual electronics behind a rs232 interface do not really care whether the input is being driven buy +-5 to +-15 volts. as long as the signal crosses the zerovolt threshold by about 2 volts. The only reason it is 12 volts is so that the cable length can be of that distance (and in practice, usually a lot longer) You will get a significant drop in the line voltage due to resistance and the cable will act like an antennae (if it is not shielded). The increase in voltage is also a noise barrier. But there may be equipment out there that is that finicky. Can't imagine why?