[Yaesu] Straight and Null Modem serial cable

[Bryan Fields]

On Monday 14 October 2002 13:29, James C. Hall, MD wrote:
> Note that the Yaesu FT-847 uses a simplified null modem configuration ie.
> pins 2, 3, and ground.  Simply go to Radio Shack and pick up some shielded
> 2-conductor audio cable and 2 male DB9 serial plugs with hoods. Solder the
> two conductors to pins 2 and 3 and the ground to pin 5.  On the other end
> do the same except SWITCH pins 2 and 3.


If you never want to think about this again, use some serial to rj45 dongles.  
Here is the system I created to handle this, it's quite useful around here.

-----


Just got back from serial hell :-(


I had about 20 different serial cables going to various places, some using
RJ-45 to DE-9/DB-25 Dongles.  The problem I ran into, is some how I mislabled
a RJ-45 cable used for serial stuff as an ethernet cable.  Blew up 2 100BaseT
cards some how (they were crappy ones, but..), and got pissed off.


I sat down and came up with a solution to this problem.  This will allow you
to use an ethernet cable in place of serial cable, with one standard jack for
9 pin and 25 pin equipment.  This will not matter if you need a null or a
strait connection, the DB to RJ-45 Dongle stays the same.


The crossover is handled in the Cable if needed, and the cable can be used
for 10/100BaseT-(4) ethernet too.  The sanderd also provides for each tx line
to be on it's own pair, with it's own ground.  This should let the cable work
to about 300 feet at 9600 Baud.


Here it is:


                Adapter       9 Pin          25 Pin
Signal RJ45   Wire Color    Connection     Connection
Tx+     1       Blue            3               2
Tx-     2       Orange          5               7
Rx      3       Black           2               3
CTS     4       Red             8               5
DCD     5       Green           1               8
Rx-     6       Yellow          5               7
RTS     7       Brown           7               4
DTR     8       White           4               20


All you may need to do is tie the ground wires together.  I just solder the
one to the other in the dongle and snap the pin in the hole.



The Cable is wired as a 100Base-T4 cable.


RJ45      A-Type          B-Type
1       White/Green     White/Orange
2       Green           Orange
3       White/Orange    White/Green
4       Blue            White/Brown
5       White/Blue      Brown
6       Orange          Green
7       White/Brown     Blue
8       Brown           White/Blue


If you need a straight trough cable wire both ends as "A-type". If you need a
null-modem wire one as "A" and the other as "B".  This cable will also now
work as an ethernet cable, its wired the same on both sides, you have a patch
cable, if it is "A" on one and "B" on the other you have a Crossover.


Cool Huh?

-- 
Bryan Fields, KB9MCI
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