brett@umd5.umd.edu (Brett Bourbin) (06/16/89)
We are trying to add a modem ot one of our RTs and we don't have any of the
modem cables, P/N 6294794, but we have many terminal cables, P/N 6298186.
What I wanted to know was the differences between the two cables, i.e. the
pinouts, so I could modify the terminal one to be used on a modem.
I looked at the Tech manuals and could not find this information, so any
help you can give would help greatly.
--
--Brett S Bourbin, Instructional Computing Programs -- Univ of Maryland
Computer Science Center, College Park, MD 20742
INTERNET: brett@umd5.umd.edu BIX: brettb DELPHI: brettbnjs@scifi.UUCP (Nicholas J. Simicich) (07/22/89)
In article <5026@umd5.umd.edu> brett@umd5.umd.edu (Brett Bourbin) writes: >We are trying to add a modem ot one of our RTs and we don't have any of the >modem cables, P/N 6294794, but we have many terminal cables, P/N 6298186. >What I wanted to know was the differences between the two cables, i.e. the >pinouts, so I could modify the terminal one to be used on a modem. The terminal cable is a "null modem" cable. The modem cable carries the signal straight through. Depending on the signals you need to carry back to the RT, (what you are going to use it for, and how desperate you are) you might just be able to swap 2 and three on the 25 pin, and block all other signals. I don't recall offhand, but I think that the terminal cable is set up for "DTR pacing", and so an approximation is to swap DTR and DSR, and to presume that RTS and CTS are crossed with a loop back to CD. A few minutes with a test meter will confirm that, and tell you more than I can remember. The modem cable is straight through with the signals being TXD, RXD, CTS, RTS, DTR, DSR, RI, DCD, ground and ???. It should be represented on the 25 pin side, anyway. The printer cable is also a "null modem" cable, but with different signals crossed. >I looked at the Tech manuals and could not find this information, so any >help you can give would help greatly. Look in the RT planning giude. Cable layouts are in there. Another place you could look is in the RT hardware technical reference manual. Did you look under the four port adapter? I don't have my manual in front of me (I'm at home) but I thout it was there. The four port cards and the planar ports use the same cables. (.....) -- Nick Simicich --- uunet!bywater!scifi!njs --- njs@ibm.com (Internet)
pgc+@andrew.cmu.edu (Paul G. Crumley) (07/23/89)
Brett, I assume you meant to type 6294704 rather than 6294794. If you really want a 6294794 don't bother with this. (BTW, the numbers you give are option numbers, not part numbers. I have found these are VERY different in IBM llingo so be careful... Asking for the right thing by the wrong name can be a very exciting experience :-) 6294704 is part number 6298240 and 6298186 is part number 6298526. 6294704 is wired like this: RT end (female) Modem end (male) name pin name pin TxD 1 TxD 2 DTR 2 DTR 20 RTS 3 RTS 4 RI 4 RI 22 5 no connection RxD 6 RxD 3 DSR 7 DSR 6 CTS 8 CTS 5 CD 9 CD 8 GND 10 GND 7 shield shield 1 6298186 is wired like this: RT end (female) Terminal end (female) name pin name pin TxD 1 RxD 3 DTR 2 DSR 6 RTS 3 CD 8 RI 4 no connection 5 no connection RxD 6 TxD 2 DSR 7 DTR 20 CTS 8 CD 8 CD 9 CTS 5 CD 9 RTS 4 GND 10 GND 7 shield shield 1 Note: RT end loops pins 3 & 8 and Terminal end loops pins 5 & 4. Though you didn't ask, this information comes from "IBM RT Personal Computer -- Planning Guide", GC23-0782. Don't try to really use an RT without one of these books. It has all the important pin-outs, part (and option) numbers, environment requirements, etc. Best regards, Paul