From owner-freebsd-questions Sun Aug 6 20:58:49 1995 Return-Path: questions-owner Received: (from majordom@localhost) by freefall.cdrom.com (8.6.11/8.6.6) id UAA06775 for questions-outgoing; Sun, 6 Aug 1995 20:58:49 -0700 Received: from distortion.eng.umd.edu (distortion.eng.umd.edu [129.2.98.6]) by freefall.cdrom.com (8.6.11/8.6.6) with ESMTP id UAA06768 for ; Sun, 6 Aug 1995 20:58:46 -0700 Received: from mocha.eng.umd.edu (mocha.eng.umd.edu [129.2.98.16]) by distortion.eng.umd.edu (8.6.10/8.6.4) with ESMTP id XAA05310; Sun, 6 Aug 1995 23:58:44 -0400 Received: (chuckr@localhost) by mocha.eng.umd.edu (8.6.10/8.6.4) id XAA04637; Sun, 6 Aug 1995 23:58:43 -0400 Date: Sun, 6 Aug 1995 23:58:43 -0400 (EDT) From: Chuck Robey To: rhh@ct.picker.com cc: questions@freefall.cdrom.com Subject: Re: (?) RJ45 Crossover Cable Question (Pin numbering) In-Reply-To: <9508062304.AA22800@elmer.ct.picker.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: questions-owner@FreeBSD.org Precedence: bulk On Sun, 6 Aug 1995, Randall Hopper wrote: > In short, does someone know the convention for numbering the pins on an > RJ45 cable connector? If the cable w/ attached connector is held in front of > you, pins on the near side of the connector and pointing up (cable attached to > the bottom), are the pins 1-to-8 numbered ascendingly from left-to-right or > right-to-left? > > ------------------------------------------------------------------------------ > > The more detailed version: > > I recently purchased an ethernet board for my FreeBSD box and am having > trouble getting it to talk to my router. I suspect that the cable might be > the problem. > > The cable (custom made by someone else) is supposed to be an RJ45 > crossover cable which I'll use to direct-connect to my home router. I've > buzzed it out to verify that pins 1-3 and 2-6 are swapped. If the answer to > the numbering convention question above is right-to-left, they are. However, > given that it isn't working and my board appears to be working fine except that > it can't put a packet on the network, I suspect that the the convention is > in-fact left-to-right, and the person that built the cable cabled it backwards. > If someone knows which is correct, please drop me some e-mail. > > Thanks in advance. > > Randall Hopper > rhh@ct.picker.com I haven't used this for anything but standard telco data interfaces, but I do know those. Here's the data from the GTE Network Interface Manual For Registered Terminal Equipment: 1 -- NC 2 -- NC 3 -- A (a control lead for keysystems) 4 -- R ("ring" lead, conventionally red in color, one of the two voice communications leads) 5 -- T ("tip" lead, conventionally green, also a voice communications lead) 6 -- A1 (another keysystem control lead, actually ground return for the A lead.) 7 -- PR (one end of the programming resistor, to set audio levels) 8 -- PC (the other end of the resistor from PR). The parenthetical comments are mine. The colors on the T and R leads are a pretty strongly adhered to convention, at least among telco people, so that can be used to identify leads 4 and 5. The interface is unfortunately used for voice only (non data modem) applications in a different way, so I wonder if you can really draw any strong conclusions. Check the interface wiring for RJ-31X and RJ-41S for comparison on that. The wiring I show is for the RJ-41S, which was used for data modem connections. Not really common for that anymore, tho. ----------------------------+----------------------------------------------- Chuck Robey | Interests include any kind of voice or data chuckr@eng.umd.edu | communications topic, C programming, and Unix. 9120 Edmonston Ct #302 | Greenbelt, MD 20770 | I run Journey2 (Freebsd 2.0R) and n3lxx (301) 220-2114 | (FreeBSD 2.0.5-snap) and am I happy! ----------------------------+-----------------------------------------------