DB25 to RJ45 Cables

These notes are mostly for myself but others might be interested. For some time, I've been using RJ45 cables to run my serial connections (remember serial). I still have a number of serial devices such as X10 controls, UPS stats, various hardware monitoring, etc..

So the RJ45 cables I use are all straight through. They plug into RJ45 to DB9 (left) or DB25 (right) connectors. If you need a straight-through cable (modems) then you should use a Non-swapped connector on both sides (or 2 swaps if that is all you have). For a swapped cable (terminals), then one of the sides should have a swapped connector and the other a non-swapped.

DB25 Pinouts

(N)on-Swapped				(S)wapped
Pin	Sig		Pin	Sig
2	TXD	Red	2	RXD	Green
3	RXD	Green	3	TXD	Red
4	RTS	Orange	4	CTS	Brown
5	CTS	Brown	5	RTS	Orange
6	DSR	Black	6	DTR	White
7	COM	Yellow	7	COM	Yellow
8	DCD	Blue	8	DCD	Blue
20	DTR	White	20	DSR	Black

DB9 Pinouts

(N)on-Swapped				(S)wapped
Pin	Sig		Pin	Sig
1	DCD	Blue	1	DCD	Blue
2	Rxd	Green	2	Txd	Red
3	Txd	Red	3	Rxd	Green
4	DTR	White	4	DSR	Black
5	COM	Yellow	5	COM	Yellow
6	DSR	Black	6	DTR	White
7	RTS	Orange	7	CTS	Brown
8	CTS	Brown	8	RTS	Orange
9	Unused		9	Unused

DB9 APC Unit (WARNING NOT TYPICAL)

(N)on-Swapped				(S)wapped
Pin	Sig		Pin	Sig
1	Rxd	Green	1	Txd	Red
2	Txd	Red	2	Rxd	Green
3	Unused		3	Unused
4	COM	Yellow	4	COM	Yellow
5	Unused		5	Unused
6	Unused		6	Unused
7	Unused		7	Unused
8	Unused		8	Unused
9	Unused		9	Unused

Labeling Notes

• Label ("N" or "S) goes on the side with the more pins
• With pins toward you, lable up, modular clip should be pointing right

          ***
Clip:     ****
          ***

        *      *
Lable:  * *    *
        *  *   *
        *   *  *
        *    * *
        *      *

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