Bob Schreibmaier <k2ph@dxis.att.com> (05/08/91)
> Can anybody out there post the definitive method of pairing (with > color code) for the AT&T PDS scheme? I saw a post in comp.dcom.lans > that gave the following diagram: > WH OR WH BL WH GR WH BR > OR WH GR WH BL WH BR WH > (RJ-45F) 1 2 3 4 5 6 7 8 > | | | | | | | | > pairs: T2 R2 T3 R1 T1 R3 R4 T4 > +--+ | +--+ | +--+ > +--------+ > The trouble I have is with pair 4. Which pin is really tip, and > shouldn't it be white/brown? Also, is pair 2 really on pins 1 and 2, > or is it on 3 and 6? I used to work on PDS about umpteen years ago (back when I had a job!). Let's see if my memory serves correctly. If I can map the pins assignments on the 8-pin jack to where they go on a 110A connector block (replacement for the old 66 blocks) we can get this right. It's a very strange mapping and I have no idea about where it came from historically. The 110A block actually is easier to understand in that it is laid out as tip-ring pair 1, tip-ring pair 2, tip-ring pair 3, and tip-ring pair 4. Like so: 1 2 3 4 5 6 7 8 | | | | | | | | 110A block T1 R1 T2 R2 T3 R3 T4 R4 The mapping of the eight-pin modular jack to 110A is: 8-pin 110A 5 (T1) 1 4 (R1) 2 1 (T2) 3 2 (R2) 4 3 (T3) 5 6 (R3) 6 7 (T4) 7 8 (R4) 8 So, actually, Tip of pair 4 is on pin 7 and Ring is on pin 8. In the PDS wiring scheme, pair 4 is typically used for powering of adjuncts via a power supply either connected locally or placed in a satellite closet. Usually had -48 volts on pin 7 and ground on pin 8. However, it was also used with the 355B and 355BF protective adapters for RTS/CTS hardware flow control with the AIM4 boards on the AT&T Information Systems Network packet data switch (if you have any interest). Lessee now ... regarding your question of color codes, I believe you have them right, but my memory is foggy on that one. But your pairing is correct. Pins 4-5 are pair 1, pins 1-2 are pair 2, pins 3-6 are pair 3, and pins 7-8 are pair 4. I sure hope this helps rather than confuses more! Bob Schreibmaier K2PH | UUCP: ...!attmail!dxis!k2ph a.k.a. "The QRPer" | Internet: k2ph@dxis.attmail.com Middletown, New Jersey | ICBM: 40o21'N, 74o8'W
pturner@eng.auburn.edu (Patton M. Turner) (05/12/91)
>> Can anybody out there post the definitive method of pairing (with >> color code) for the AT&T PDS scheme? >> The trouble I have is with pair 4. Which pin is really tip, and >> shouldn't it be white/brown? > Lessee now ... regarding your question of color codes, I believe you > have them right, but my memory is foggy on that one. You are correct in thinking pair 4 should be white/brown. The color codes are: blue 1 white 0 orange 2 red 5 green 3 black 10 brown 4 yellow 15 slate 5 violet 20 Add the values together to get the pair number. If there are more than 25 pair colored binders will be used. Mutiply the binder number by 25 and add to the pair number. It's really just a base 5 numbering system. This works for up to 625 pair. If I remember correctly, 1000 pair cable has a white-blue binder around the first 500 pair and a white-orange binder around pair 500-1000, but I beleve this is the only exception. Hope this helps. Pat Turner Auburn Univeristy, AL Internet> pturner@eng.auburn.edu Packet> KB4GRZ