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Path: sserve!newshost.anu.edu.au!munnari.oz.au!news.Hawaii.Edu!ames!haven.umd.edu!news.umbc.edu!europa.eng.gtefsd.com!uunet!world!ksr!jfw From: jfw@ksr.com (John F. Woods) Newsgroups: comp.os.386bsd.questions Subject: Re: FreeBSD multiport serial troubles... Message-ID: <35598@ksr.com> Date: 19 Nov 93 13:36:54 EST References: <CGorE5.23K@swi.psy.uva.nl> <2cglg6$hm@wzv.win.tue.nl> Sender: news@ksr.com Lines: 36 guido@gvr.win.tue.nl (Guido van Rooij) writes: >tromp@swi.psy.uva.nl (Tromp Jolanda) writes: >>I've tried various NULL modem cables and even tested the cables and >>the terminal by connecting it to another machine (Mac). The Mac could >>both read and write from the terminal. But the FreeBSD won't read the >>port. >You should have a real null modem cable. So on a 9 pin d-connector: >1-1 >2-3 >3-2 >4-6 >6-4 >7-8 >8-7 Note that Macs do not have an RS-232 port, they have an RS-422 (differential) port. With a short cable and some care, you can make RS-422 and RS-232 interoperate, but it's real easy to screw up. First, by "the FreeBSD won't read the port", do you mean you get some kind of error indication (like maybe "no such device") when you do the read? That might be a kernel configuration problem. If the read appears to hang, it might be that the port is in ^clocal mode and the carrier-detect line is floating; try enabling clocal. If the read appears to get garbage, while the Mac is able to correctly read characters, it's most likely cabling; it might also be that the Mac and the PC disagree on parity or number of bits per character (I found getty, on NetBSD anyway, disturbingly difficult to get correctly configured). The cable I used between my Mac and (NetBSD) PC was just four wire twisted- pair phone cable; TXD and RXD were red and yellow, respectively, with green and black being soldered together and attached as ground at the PC end (one of green and black was used as "ground" on the Mac end, I forget which; since the "ground" pin is really one of RXD- and TXD-, at least on the cable adapter I used, you'll probably find that one of them works better than the other; keep the soldering iron hot :-).