DE9 to DE25 via RJ45

[minicompbx]

Good afternoon everybody,

I have an another question. I am learning serial cabling.
Here is my situation :

I would like to connect to switch using serial port from my computer.

DCE : My switch nortel have DB9 Male pin

DTE : My computer serial port have DB25 Male pin

So,
I bought DB9 Female to RJ45 Adapter :

http://ca.startech.com/Cables/Seria...-RJ45-Modular-Adapter-Female-to-Female~GC98FF

and DB25 Female to RJ45 Adapter :

http://ca.startech.com/Cables/Seria...to-RJ45-Modular-Adapter-Female-Female~GC258FF

Switch DB9-F------------RJ45-------------------DB25-F PC

I would like to know how I have to connect the each pin (8 colors)in both side. DB9 and DB25

As some of you are expert on this, can you guide me to make to work.

Thank you for your kind help.

 

[TouchToneTommy]

These adapters let you "roll your own", picking which signal you put to which pin in the modular jack.

Do a google on Serial Port Pinouts, for both 9 and 25 pin. Wikipedia has a pretty good entry.

Then connect Transmit of one side to Receive of the other, and vice-vera, connect Ground to Ground. This would be the minimum connections necessary.

 

[minicompbx]

I already search online before posting here. As I am newbie on it, I was waiting some guide.

As my research has done, I already connect the DB-9 Female :

RJ-45 DB-9 Pin
1 (Blue) 7
2 (Orange) 4
3 (Black) 3
4 (Red) 5
5 (Green) 5
6 (Yellow) 2
7 (Brown) 6
8 (Gray) 8


Anybody.... to give more details for RJ-25 and if the cabling is correct or not for DB-9


Thank you.

 

[TouchToneTommy]

http://www.lammertbies.nl/comm/cable/RS-232.html

On the DB-9 end,
2=Receive Data
3=Transmit Data
5=Ground

On the DB-25 end,
3=Receive Data
2=Transmit Data
7=Ground

In your pinout above, you've got the DB-9 Receive (Pin 2) leaving on the RJ-45 Pin 6 (Yellow), so at the DB-25 end, use the same RJ-45 Pin (6) and color (Yellow) but connect it to the DB-25 Pin 2 (Receive of DB-9 to Transmit of DB-25)

Your DB-9 Transmit (Pin 3) is on RJ-45 Pin 3(Black), so at the DB-25 end connect RJ-45 Pin 3 (Black) to DB-25 Pin 3 (Transmit of DB-9 to Receive of DB-25)

And your Ground (DB-9 Pin 5) on the DB-9 side is on RJ-45 Pin 4 and/or 5 (?), so extend it to Pin 7 of the DB-25.

 

[wires]

Since you are going DTE DCE you don't need a null modem or crossover configuration. Notice how the pin configurations change:

25 pin DTE devices transmit on pin 2 and receive on pin 3.
25 pin DCE devices transmit on pin 3 and receive on pin 2.
9 pin DTE devices transmit on pin 3 and receive on pin 2.
9 pin DCE devices transmit on pin 2 and receive on pin 3.

If there is no handshaking (flow control) or XON/XOFF handshaking three wires will work. However if there is hardware handshaking you need more pins.

Here is the full pinout I use for straight cables:

DB9
3 Rd (red)
2 Gr (green)
7 Or (orange)
8 Br (brown)
5 Bk (black)
1 Yl (yellow)
4 Bu (blue)
6 Wh (white or gray some have one some the other)

DB25
2 Rd
3 Gr
4 Or
5 Br
7 Bk
8 Yl
20 Bu
6 Wh

Over the years these colors have stayed stable over quite a few manufacturers. YMMV.

My guess is that your Nortel switch has no flow control so all you need is 3 wires.

DB9
3 Rd (red)
2 Gr (green)
5 Bk (black)

DB25
2 Rd
3 Gr
7 Bk

Just so there is no confusion the first line (3 Rd) means put the red wire in position 3 of the DB9 shell. There are numbers molded in the plastic. They are very small and can be confusing depending on gender (of the connector).

 

[minicompbx]

Thank you for you whole information

I just find out from my network administrator, the nortel switch is DTE instead of dce.

So, it should be DTE to DTE

And, what is exactly Flow control

Knowing that, how does the cabiling should be changed.
I found this online, does this is correct, please let me know.

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

In the meantime, I doing all the test with the information that you guys kindly provided.

Again, thanks for your help.

 

[wires]

The information I find online on Nortel switches say this:

Bit Per Second: 9600
Data Bits: 8
Parity: None
Stop Bits: 1
Flow Control: None

So all you need is 3 wires TD, RD, SG since there is no handshaking (flow control).

Since both are DTE you will need to swap the TD and RD on ONE end. So this should work:

DB9 (draw an X on the shell to indicate crossover)
2 Rd (red)
3 Gr (green)
5 Bk (black)

DB25
2 Rd
3 Gr
7 Bk

Handshaking or flow control are two words describing the same thing, signals to prevent overflowing the input buffer on the receive side of a serial link. At lower speeds (like 9600) with modern hardware there is no need for flow control since the input buffers are large enough and the processing of received character is fast enough to keep up. At higher speeds or with slower equipment flow control must be used to keep the data uncorrupted. The simplest flow control is XON/XOFF where the receiving unit sends a XON to indicate ready to receive communications and a XOFF to pause communications. More advanced flow control uses hardware handshaking using the DTR DSR RTS and CTS conductors asserted to logic high or logic low.

The pinout you have above is a full null modem cable. While it will likely work it is overkill if there is on flow control.

 

[minicompbx]

I did tried what you said but still not working out.

With my research, I found online and I did try and it work. But that was not want I wanted. I was able to communicate with switch :
What works now :

db9----rj45---db9

Here are the pinout i configure and it's works...

DB-9 Pin to PC
1 Empty
2 Yellow(6)
3 Black(3)
4 Orange(2)
5 Green & Red (5,4)
6 Brown (7)
7 Blue(1)
8 White (8)
9 -Empty

DB-9 Pin to Switch
1 Empty
2 Yellow(6)
3 Black(3)
4 Orange(2)
5 Green & Red (5,4)
6 Brown (7)
7 Blue(1)
8 White (8)
9 -Empty

what i want is :
DB9-F---------RJ45------DB25-F PC

so All I want to do is to put DB-25 Pin in pc side instead of db-9

Do you have any idea for which color go on which pin depending on the information I gave above.

Thank you one more time.

Have a great day.

 

[wires]

If this works:

DB-9 Pin to PC
2 Yellow(6)
3 Black(3)
5 Green & Red (5,4)

DB-9 Pin to Switch
2 Yellow(6)
3 Black(3)
5 Green & Red (5,4)

Then one device is DTE and the other is DCE since there is no crossing of the RD and TD lines. Translated to DB9->DB25 the pinout (following standards such as they are) is:

DB9
2 Gr (green)
3 Rd (red)
5 Bk (black)

DB25
2 Rd
3 Gr
7 Bk

(just like I said 6 Mar 12 1:40)

All the other wiring you have does nothing. For example the blue wire on pin 7 would have to go to pin 8 on the other end to actually do anything (RTS-CTS handshake). All you need are 3 wires, TD RD and SG.

Don't make this harder than it is. Most hubs/switches are DTE. All PCs I have ever seen are DTE. So that means that you need a crossover like this:

DB9 (draw an X on the shell to indicate crossover)
2 Rd (red)
3 Gr (green)
5 Bk (black)

DB25
2 Rd
3 Gr
7 Bk

or this

DB9 (draw an X on the shell to indicate crossover)
2 Rd (red)
3 Gr (green)
5 Bk (black)

DB9
2 Gr
3 Rd
5 Bk

However you are saying straight works... What do I know, I've only wired hundreds of RS232/RS485 devices together...

I can't imagine you need more than 3 wires. The relevant pins are 2,3 and 5 (plus 7 if you are using 25 pin connectors).

5 goes to 5 or 7 on a 25 pin it's Signal Ground (SG).

2 either goes to 2 or 3 it's Transmit Data TD or Receive Data RD depending on DTE/DCE or 9 vs 25 pin connectors.

3 either goes to 3 or 2 it's Transmit Data TD or Receive Data RD depending on DTE/DCE or 9 vs 25 pin connectors.

How hard can that be?

Are you SURE your 25 pin serial card works. Since you seem to indicate it is on the PC end it is likely fairly old. Are you SURE it is a serial connector? Is it a male connector? 25 pin female connectors have been used for other devices on PCs.

 

[minicompbx]

Thank you guys for your all kind of help.

It was very helpful.

Finally, I was able to make it work.

If anybody is interest about my cabling or need more details, please take a look at my google documents link below :

https://docs.google.com/document/d/1ZiTsJ9hejNIHMRdNcfTx2WjZinuj09WPqqwRc65FYkE/edit

It work's great now after long research and your's help.

Have great day.

 

[wires]

While I'm glad you got it to work there is a reason TD, RD, and SG are supposed to be on red, green and black. A lot of serial wiring is done on 4, 6 and 8 conductor cable (sometimes silver satin). The pinouts need to be compatible across the varying wire counts so the three most important conductors are on the center most positions, black, red, green and yellow (which is mostly unused DCD).

Hopefully no one will follow your lead on using red and green for SG.

Here is my cheat sheet:

II  X             II  X 
 DB9    Co  Fn     D25      45    110   4pr
3   2   Rd  TD    2   3      4     2    BL
2   3   Gr  RD    3   2      5     1    wBL
7   8   Or  RTS   4   5      2     4    OR
8   7   Br  CTS   5   4      7     7    wBR
5   5   Bk  GND   7   7      3     5    wGR
1   -   Yl  DCD   8   -      6     6    GR
4   6   Bu  DTR   20  6      1     3    wOR
6  1/4  Wh  DSR   6  8/20    8     8    BR

Straight at computer
Crossed at peripheral

4 wire only TD, RD, GRD (& DCD)

DB9 II (straight)
1-5  YL, GR, RD, BU, BK
6-8  WH, OR, BR

DB9 X (null modem plug)
2-5  RD, GR, WH, BK
6-8  BL, BR, OR

Lantronix/Cisco X (special crossover)
2-5  BK, YL, BR, RD+GR
6-8  OR, WH, BL

Serial Printer        
PC = straight DB9 (II)
Printer = special DB25
2=Green 3=Red 7=Black
20=Yellow,White,Brown

DB25 HW loopbacks (spit plug)
4to5, 6to20

This has been in my Palm/Android for over 15 years and has yet to fail me.

 

[minicompbx]

I will keep a copy of your cheat sheet for future purpose.

Thank you for the information and help.