Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!rutgers!ames!ucbcad!ucbvax!sdcsvax!brian From: brian@sdcsvax.UCSD.EDU (Brian Kantor) Newsgroups: comp.periphs,comp.terminals,comp.dcom.lans Subject: Re: Telco-style push down blocks and stranded cable Message-ID: <2440@sdcsvax.UCSD.EDU> Date: Sat, 10-Jan-87 10:20:19 EST Article-I.D.: sdcsvax.2440 Posted: Sat Jan 10 10:20:19 1987 Date-Received: Sat, 10-Jan-87 22:45:41 EST References: <2551@phri.UUCP> <2856@osu-eddie.UUCP> <1634@hoptoad.uucp> <1635@hoptoad.uucp> Reply-To: brian@sdcsvax.UCSD.EDU (Brian Kantor) Distribution: world Organization: UCSD wombat breeding society Lines: 73 Xref: mnetor comp.periphs:128 comp.terminals:134 comp.dcom.lans:136 Here at UCSD we have been using punchblocks (66-type) for some time. The system we devised for using them is that each computer port is connected to modular plugs (we use the ones from MOD-TAP), and a "hydra" which takes the individual modular plugs and brings them to telco-style 50-pin plug inside the computer system (Unibus cabinet, etc). A 25-pair cable with appropriate connectors takes this to a dual-connectorized 66 block on the wall. For ports which connect to our LAN or which run to rooms with clusters of terminals, a similar cable leaves the other half of the 66-block and runs either to a hydra and modular plugs into the LAN box, or to another punchblock (single connectorized is ok here) and punched-down inside wire to terminals, or to a "harmonica" (the other sex of a hydra: modular jacks on a 50-pin connector). This way my cross-connect wiring for the majority of our connections (in the computer room, at least) consists of bridging clips and is very fast to connect. Essentially, all RS-232 connections entering the computer room terminate on a punchblock. In laboratories and terminal rooms where I'm likely to have a cluster of connections (i.e., more than 2), I place a 66-block with 50-pin connector and run a 25-pair cable with connectors back to the computer room, where it terminates in another 66-block. Cross-connect is done by bridging clips or 3-pair inside wire. For less-dense terminals, either a punchblock is nearby serving several rooms, or I string longer runs of 3-pair. I've got 200 and 300 foot runs running at 19,200 and 9600 bps with no problems. I've also bought a couple of items for troubleshooting - I have a nifty little connector that you can slip onto the punchblock terminals and plug a modular connector into - that connects to a breakout box or datacomm analyzer and you can tap into any line in or out of the computer without unplugging anything. If you need to isolate a connection, you can pop the bridging clips, or simply unplug the modular plug at the terminal or computer. Fast fast FAST to troubleshoot! Standardization: We chose a 6-conductor scheme (which gives 8 ports on a punchblock, cable, hydra, or harmonica) so that we could wire modems, printers, and terminals the same way. (Our LAN boxes look like modems and need DTR and CD in addition to the normal TD, RD, and SG, so we have one spare wire left over. On modems, that spare wire is RI.) We use only two kinds of connectors (called a 260 and a 523 by Mod-Tap) and stock them in both sexes. A cable with a 260 connector on both ends is a straight-through cable suitable for connecting to a modem or LAN box on one end, and a computer or terminal on the other (assuming the computer is DTE, which most are these days). A directly-wired terminal (or other DTE device, such as a printer) will still have a 260 connector on it, but the port on the computer will have a 523 connector for that line, which gives a null modem to connect the DTE to the computer DTE port. Our modem telephone lines are wired similarly, but we use 4-conductor cable there to match the 2-pair inside wiring that the phone company uses. (By the way, ThePhoneCo is happy to terminate incoming lines on one of our connectorized 66 blocks. We just tell them to "terminate on customer-provided RJ21X" and they do it just right.) With 4-conductor modular stuff, you get 12 per cable/block/hydra/harmonica. All this stuff is available from MOD-TAP. We buy a lot of it from other people too. What with the installation of our LAN and rewiring most of the campus, we've probably installed more than 2000 RS-232 connections using variations of this system, and found it to work quite well. DEC and others have similar systems with slightly different standards. Brian Kantor UCSD Office of Academic Computing Academic Network Operations Group UCSD B-028, La Jolla, CA 92093 USA Disclaimer: just because I said it doesn't mean its right. Think for yourself.