robert4@garfield.UUCP (Robert Pitt) (03/19/88)
Does anyone have the proper wiring for a 9-pin RS232 null modem?? I know the configuration for a 25-pin NM, but don't know which pins become which in a 9-pin cable. Many thanks, Rob _________________________________________________________________ robert4@garfield.UUCP R.D. Pitt rpitt@mun.bitnet English Department robert4@.mun.cdn Memorial University rpitt@kean.mun.cdn St. John's, Newfoundland 70721,320 CIS CANADA, A1C 5S7
W8SDZ@SIMTEL20.ARPA (Keith Petersen) (03/20/88)
From the archives at SIMTEL20...
A p p l i c a t i o n N O T E
Following is a schematic diagram for the construction of a cable
which connects the PC/AT's 9-pin serial I/O port to devices using
a standard DB-25-pin connector:
AT Serial Name DB-25 connector
1 CD 8
2 RD 3
3 TD 2
4 DTR 20
5 SG 7
6 DSR 6
7 RTS 4
8 CTS 5
9 RI 22
--Keith Petersen
Arpa: W8SDZ@SIMTEL20.ARPA
Uucp: {decwrl,harvard,lll-crg,ucbvax,uunet,uw-beaver}!simtel20.arpa!w8sdz
GEnie: W8SDZwall-rt@cscosl.ncsu.edu (Richard Todd Wall) (01/17/90)
I have an IBM PC XT clone running MSDOS 3.3. I've been trying to
connect my PC to a terminal I have in my room but I can't even get it
to direct output out to the terminal. I have done
MODE COM1:1200,E,7,1 and that works ok, but when I type
DIR >COM1 it gives a write fault writing device error.
Could someone please tell my how my null modem cable should be
set up?? I've tried 3 different configurations so I'm open to
suggestions. Thanks.
- Todd Wall -
wall-rt@cscosl.ncsu.edulance@helios.ucsc.edu (Lance Bresee) (01/18/90)
In article <1990Jan17.153819.12882@ncsuvx.ncsu.edu> wall-rt@cscosl.UUCP (Richard Todd Wall) writes: > Could someone please tell my how my null modem cable should be >set up?? I've tried 3 different configurations so I'm open to >suggestions. Thanks. > Basically, you need to swap pins 2 and 3. You need to have pins 7 and 1 for signal and chassis ground respectively. Now the fun starts! The rest depends on the handshake or control system your terminal requires, and the dtr/cts system IBM uses. It may be that your terminal uses xon/xoff protocal, and generates NO control signals. In such a case, you have to dummy them out on your cable by connecting the output control lines from the PC to the input. Also, you have to get xon/xoff for your PC. There were a series of articles on how to do this on the net a while back, and some assembler source. We copied it and have been successfully running a laser printer using xon/xoff for some time. Check the IBM technical reference for better data on IBM's required control lines. Check your monitors manual for the proper protocall to use. lance
darcy@druid.uucp (D'Arcy J.M. Cain) (01/20/90)
In article <1990Jan17.153819.12882@ncsuvx.ncsu.edu> wall-rt@cscosl.UUCP (Richard Todd Wall) writes: > > I have an IBM PC XT clone running MSDOS 3.3. I've been trying to >connect my PC to a terminal I have in my room but I can't even get it >to direct output out to the terminal. I have done >MODE COM1:1200,E,7,1 and that works ok, but when I type >DIR >COM1 it gives a write fault writing device error. > I'll suggest the obvious here. It doesn't matter what your mode statement is. The important thing is that it match your terminal. > Could someone please tell my how my null modem cable should be >set up?? I've tried 3 different configurations so I'm open to >suggestions. Thanks. > 1 --- 1 2 --- 3 3 --- 2 4 --- 5 5 --- 4 6 --- 20 20 --- 6 7 --- 7 In some cases you may have to tie 6 & 8 on the same end together as well. -- D'Arcy J.M. Cain (darcy@druid) | Thank goodness we don't get all D'Arcy Cain Consulting | the government we pay for. West Hill, Ontario, Canada | No disclaimers. I agree with me |