Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!jarthur!nntp-server.caltech.edu!pooh!madler From: madler@pooh.caltech.edu (Mark Adler) Newsgroups: comp.sys.next Subject: Re: RS423 - RS232 line levels (volts) different Message-ID: <1991Jan1.035440.18016@nntp-server.caltech.edu> Date: 1 Jan 91 03:54:40 GMT References: <1990Dec31.170055.8728@uokmax.ecn.uoknor.edu> Sender: news@nntp-server.caltech.edu Organization: California Institute of Technology, Pasadena Lines: 20 Nntp-Posting-Host: pooh.caltech.edu Lawrence Clarke (lclarke@questor.wimsey.bc.ca) warns: >> 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. If it cannot handle +/-5v, then it is not built to RS-232 specs. The specs allow a transmitter to use anything from +/-5v to +/-25v and require that a receiver respond to signals as low as +/-3v. The two volt difference is to allow for a voltage drop on long cables (in reality, the drop is much less than that). If you are having problems connecting RS-232 to the NeXTstation, blame everything else (wiring, ground loops, modem not on, etc.) before thinking that it is incompatible voltage levels. It may be, but it's quite unlikely. Mark Adler madler@pooh.caltech.edu