nullmodem connection

09-27-2002, 06:53 PM

How hard is it to setup a serial null modem connection in redhat7.3? I might need one in the immediate future to connect to a console (no keyboard or monitor connected to it) to repair a hpux load on a scsi hard drive.

**pbharris** · 09-27-2002, 07:14 PM

it would be as easy as anything, all a null modem does is switch the placement of wires such that the uart can connect to another uart. after that set up minicomm and you should be set.

**Schotty** · 09-27-2002, 07:45 PM

I would have to agree with pbharris. It should be a breeze.

**pbharris** · 09-27-2002, 07:55 PM

schotty agrees! i would say you can take our advice to the bank!

**Schotty** · 09-27-2002, 07:56 PM

Let us know what it cashes in for then

**Pantheus** · 09-29-2002, 08:01 AM

Code:

Common Null-Modem Connection
Signal Name             DB-25 Pin DB-9 Pin        DB-9 Pin DB-25 Pin  
FG (Frame Ground)             1                            1                            FG
TD (Transmit Data)              2       3                   2               3           RD
RD (Receive Data)              3        2                   3               2           TD
RTS (Request To Send)      4        7                   8               5           CTS
CTS (Clear To Send)           5        8                   7               4           RTS
SG (Signal Ground)             7        5                   5               7           SG
DSR (Data Set Ready)         6        6                   4             20          DTR
CD (Carrier Detect)              8        1                   4             20          DTR
DTR (Data Terminal Ready) 20      4                    1              8           CD
DTR (Data Terminal Ready) 20      4                    6              6           DSR

09-29-2002, 11:26 AM

Here is what Im working on. Monday night I start my new job with Lockheed Martin working on HP J9000 computers, vme processors, and some other stuff running hpux 10, in a ruggedized rack for military use (on Navy ships). One of the consoles is a dual processor seutp, but not in the normal sense. It has 2 seperate mobos (which are very slow), the bottom one is connected to the monitor and keyboard and network , while the top one is connected to the network also, but no monitor or keyboard. So, I need to build a serial nullmodem cable with a special military connector on one end, and then setup my redhat laptop to talk to it for doing a reload through an external scsi drive. Whew. Thanks that it. I will let you all know how it goes when I get everything put together.