Data communication Cables

Crimp to sub D

In PCs, a sub-D connector (COM, Game / Midi or LPT) is often connected to a crimp or IDC (Insulation Displacement Connector) by means of a ribbon cable. IDCs have two rows of pins. One is even, the other odd numbered;


    +-----+               +-----+
 1  | * * |  2         2  | o o |< 1
 3  | * * |  4         4  | o o |  3
 5    * * |  6         6  | o o  | 5
 7  | * * |  8         8  | o o |  7
 9  | * * | 10        10  | o o |  9
    +-----+               +-----+

 Male (motherboard)   Female (cable) 

Pin 1 on the connector is marked with a triangle. The corresponding wire is red.

There are two ways of connecting these to a DE-9, DA-15 or DB-25 connector;

  1. Match the pin numbers. AKA straight-through.
  2. Connect a row on the IDC to a row on the sub-D. AKA crossed wiring.
    This system is well suited for crimp sub-D connectors.

Match the pin numbers

DE-9


DE-9	IDC-10

1	1
2	2
3	3
4	4
5	5

6	6
7	7
8	8
9	9

Pin 10 on the IDC is not used.

DE-9 Male


      1 2 3 4 5
  -----------------
   \  * * * * *  /
     \ * * * * /
       -------
       6 7 8 9

1     DCD       6     DSR
2     RXD       7     RTS
3     TXD       8     CTS
4     DTR       9     RI
5     GND

IDC


DCD     1  * *  2       RXD
TXD     3  * *  4       DTR
GND     5  * *  6       DSR
RTS     7  * *  8       CTS
RI      9  * * 10       NC (Not Connected) or Key

This system is used by many Asus motherbords.

Match the rows

DE-9


DE-9	IDC-10

1	1
2	3
3	5
4	7
5	9

6	2
7	4
8	6
9	8

Examples

This page shows pictures of both; Internal Serial Cables for COM2

Game / Midi

This system was used on the old ISA multi-IO cards.
It's also compatible with many ASUS motherboards.

DA-15 Female


        8 7 6 5 4 3 2 1
    -----------------------
     \  o o o o o o o o  /
       \ o o o o o o o /
         -------------
         1 1 1 1 1 1
         5 4 3 2 1 0 9


 1    + 5 V (common for 1st set of pots)
 2    Button 1
 3    X Axis 1 (0-100 kOhm)
 4    GND (ground for button 1)
 5    GND
 6    Y Axis 1 (0-100 kOhm)
 7    Button 2
 8    + 5 V

 9    + 5 V (common for 2nd set of pots)
10    Button 4
11    X Axis 2 (0-100 kOhm)
12    Midi TX
13    Y Axis 2 (0-100 kOhm)
14    Button 3
15    Midi RX

IDC-16


 +5V       1  * *  2     +5V
 J1B1      3  * *  4     J2B1
 J1CX      5  * *  6     J2CX
 GND       7  * *  8     Midi Out
 GND       9  * * 10     J2CY
 J1CY     11  * * 12     J2B2
 J1B2     13  * * 14     Midi in
 +5V      15  * * 16     NC (Not Connected) or Key

Pin 16 is not used.

On PCB's you will often find a different way to number 16 pin connectors;


		Or;

 1  * *  9		1  * *  9
 2  * * 10		2  * * 10
 3  * * 11		3  * * 11
 4  * * 12		4  * * 12
 5  * * 13		5  * * 13
 6  * * 14		6  * * 14
 7  * * 15		7  * * 15
 8  * * 16 / NC		8  *   16 / Key

This corresponds to the DA-15 numbering.

Some Midi keyboards have a DA-15 connector. They get their power from the game port.

LPT

Some ASUS motherboards use this system.


DB-25    IDC26

 1      1
 2      3
 3      5
 4      7
 5      9
 6     11
 7     13
 8     15
 9     17
10     19
11     21
12     23
13     25

14      2
15      4
16      6
17      8
18     10
19     12
20     14
21     16
22     18
23     20
24     22
25     24

Pin 26 on the IDC is not used.

DB-25 Female


      1 1 1 1
      3 2 1 0 9 8 7 6 5 4 3 2 1
  ---------------------------------
   \  o o o o o o o o o o o o o  /
     \ o o o o o o o o o o o o /
       -----------------------
       2 2 2 2 2 2 1 1 1 1 1 1
       5 4 3 2 1 0 9 8 7 6 5 4

 1    -STROBE   14    -AUTOFEED
 2    D0        15    -ERROR
 3    D1        16    -INIT PRINTER
 4    D2        17    -SELECT INPUT
 5    D3        18    GND
 6    D4        19    GND
 7    D5        20    GND
 8    D6        21    GND
 9    D7        22    GND
10    -ACK      23    GND
11    BUSY      24    GND
12    P. END    25    GND
13    SELECT

IDC


-STB    1  * *  2    -AFD
D0      3  * *  4    -ERROR
D1      5  * *  6    -PINIT
D2      7  * *  8    -SLIN
D3      9  * * 10    GND
D4     11  * * 12    GND
D5     13  * * 14    GND
D6     15  * * 16    GND
D7     17  * * 18    GND
-ACK   19  * * 20    GND
BUSY   21  * * 22    GND
PE     23  * * 24    GND
SLCT   25  * * 26    NC (Not Connected) or Key

Null Modem cable


RXD--------\   /--------RXD
             X 
TXD--------/   \--------TXD

RTS--------\   /--------RTS
             X
CTS--------/   \--------CTS

DTR--------\   /--------DTR
             X
DSR--*-----/   \-----*--DSR
     |               |
DCD--+               +--DCD

GND---------------------GND

The screen of the cable should be connected (soldered) to the connector shell at both ends of the cable.

Null Modem cable with 9 pins connector


        5 4 3 2 1
    -----------------
     \  o o o o o  /
       \ o o o o /
         -------
         9 8 7 6

        DE-9 Female

 2 --------\   /--------  2
             X 
 3 --------/   \--------  3

 7 --------\   /--------  7
             X
 8 --------/   \--------  8

 4 --------\   /--------  4
             X
 6 --*-----/   \-----*--  6
     |               |
 1 --+               +--  1

 5 ---------------------  5

Null Modem cable with 25 pins connector

        1 1 1 1
        3 2 1 0 9 8 7 6 5 4 3 2 1
    ---------------------------------
     \  o o o o o o o o o o o o o  /
       \ o o o o o o o o o o o o /
         -----------------------
         2 2 2 2 2 2 1 1 1 1 1 1
         5 4 3 2 1 0 9 8 7 6 5 4

               DB-25 Female

 3 --------\   /--------  3
             X 
 2 --------/   \--------  2

 4 --------\   /--------  4
             X
 5 --------/   \--------  5

20 --------\   /-------- 20
             X
 6 --*-----/   \-----*--  6
     |               |
 8 --+               +--  8

 7 ---------------------  7

Null Modem cable 25 pins to 9 pins


25 pins                 9 pins

 3 --------\   /--------  2
             X
 2 --------/   \--------  3

 4 --------\   /--------  7
             X
 5 --------/   \--------  8

20 --------\   /--------  4
             X
 6 --*-----/   \-----*--  6
     |               |
 8 --+               +--  1

 7 ---------------------  5

LapLink cable

This cable can also be used for interlink and plip


D0----------------------ERROR
D1----------------------SELECT
D2----------------------PE
D3----------------------ACK
D4----------------------BUSY

ACK---------------------D3
BUSY--------------------D4
PE----------------------D2
SELECT------------------D1

ERROR-------------------D0

GND---------------------GND

                          1 1 1 1
        1 2 3 4 5 6 7 8 9 0 1 2 3
    ---------------------------------
     \  * * * * * * * * * * * * *  /
       \ * * * * * * * * * * * * /
         -----------------------
         1 1 1 1 1 1 2 2 2 2 2 2
         4 5 6 7 8 9 0 1 2 3 4 5

                DB-25 Male

 2 --------------------- 15
 3 --------------------- 13
 4 --------------------- 12
 5 --------------------- 10
 6 --------------------- 11

10 ---------------------  5
11 ---------------------  6
12 ---------------------  4
13 ---------------------  3

15 ---------------------  2

18 ... 25 -------------- 18 ... 25

UTP Cross cable


+ TXD ----\       /---- + TXD
            \   /
- TXD ----\   X   /---- - TXD
            X   X
+ RXD ----/   X   \---- + RXD
            /   \
- RXD ----/       \---- - RXD


    1 ----\       /---- 1
            \   /
    2 ----\   X   /---- 2
            X   X
    3 ----/   X   \---- 3
            /   \
    6 ----/       \---- 6

V36 - RS449 to V35 cable

I wonder to which extend these standards are in fact compatible.


  1  Scr   A
  2
  3
  4  ---   P
  5  ---   Y
  6  ---   R
  7  ---   C
  8  ---   V
  9  ---   D
 10  ---   L
 11  ---   E
 12  ---   H
 13  ---   F
 14  ---   N
 15
 16
 17  ---   U
 18  ---  NN
 19  GND   B

 20  GND
 21
 22  ---   S
 23  ---  AA
 24  ---   T
 25
 26  ---   X
 27
 28
 29
 30
 31
 32
 33
 34
 35  ---   W
 36
 37  GND

The pins marked `GND' are connected to each other.
The pin marked `Scr' is connected to the shield.