Re: Custom CAT-5 / DB-9 serial cables

In regard to DB9 to DB25 you are misinformed.
The correct pinning would be as follows...
1. looking at the RJ45, the color of wire for the pins is

1. Blue
2. Orange
3. Black
4. Red
5. Green
6. Yellow
7. Brown
8. White or Grey

I have been told that the colors could vary, though this is the color arrangment I have always seen. It is the same for both the DB25 and DB9 adapters.

On the other side, the DB25 pins are as follow

1. Frame Ground
2. Transmit Data
3. Receive Data
4. Request to Send
5. Clear to Send
6. Data Set Ready
7. Signal Ground
8. Data Carrier Detect
20. Data Terminal Ready

there are obviously 16 other pins. These are not required (actually several of these 9 are not). You can ignore pin#1 or tie it to pin#7. pins 6,8, and 20 can be tied to each other or tied back (ie 6 & 8 on one side to 20 on the other).

on the DB9 the pins are as follows

1. Data Carrier Detect
2. Receive Data
3. Transmit Data
4. Data Terminal Ready
5. Signal Ground
6. Data Set Ready
7. Request to Send
8. Clear to Send
9. -- I do not know --

so, the point here is... if the colors are the same on both RJ45's and are as stated above... Here is how you would wire the DB9 and DB25 for a straight-through cable as needed.

RJ45 DB9 DB25 Color

---- ---- ---- -----

1 1 8 Blue

2 2 3 Orange

3 3 2 Black

4 4 20 Red

5 5 7 Green

6 6 6 Yellow

7 7 4 Brown

8 8 5 White