Here are several diagrams and tables explaining parallel
port, serial port and null-modem configurations, which are mostly available on
Internet. I was forced to provide this information on the Internet by myself
when my search began for getting Laplink Cable or Null Modem Cable to transfer
data from one Win95 PC to another Win95 PC in Sept-97. I bought the laplink
cable in the market and that served my purpose as I successfully transferred
data from "HOST" to "GUEST" computer with Laplink. But also I was bit worried
with the cost of LAPLINK cables available in the market as I purchased it at at
least thrice the cost of its material cost. Let's discuss this in Indian Rupees.
I purchased Laplink cable at Rs.120/- in the market. But the material cost I
calculated was only Rs.50/- if we prepare this at home if you have a logically
working BRAIN and a little bit knowledge of soldering wires, which most of us do
while repairing toys or portable radios. So I did opened the D-25 Female pins of
my Laplink cable and studied the colour combinations of wires and prepared the
following PINOUT Chart for those who want to make LAPLINK Cable at home. (THIS
IS JUST AN INFO PAGE, BUT PLEASE USE THIS INFO AT YOUR OWN RISK.)
The other information available on this page are the collection of
information available on Internet elsewhere and also from someone from geocities
whose name I forgot. But its somebody called Acclaim@geocities.com. Here we go with
the duscussion....
A PARALLEL port can consist of only 25 pin port adapter called a DB-25 and a
serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin
adapter called a DB-9 port adapter. Whether the port is a 9 pin or 25 pin it can
accomplish all of the same tasks that serial port communications have been
designed for.
Each adapter can be a male type connector with pins or a female type adapter
with tiny holes. Generally a PRINTER port (called LPT1) on the back of a
computer is female type adapter and we need to use MALE DB-25 pin cable on it
for PRINTER connection or for parrallel LAPLINK cable.
And a COM port on the back of a computer is male for the serial ports but it
may not necessarily be. Below are diagrams of a DB-25 and DB-9.
(Each diagram on this page is the
view you see when you look into the end of the cable from the outside of the
cable.)
The "o" characters represent holes, the "." characters represent pins. A
DB-25 looks like this...
Diagram #1
Female: Male:
_____________________________ _____________________________
\ 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 / \ . . . . . . . . . . . . /
------------------------- -------------------------
And a DB-9 is like this...
Diagram #2
Female: Male:
_____________ _____________
\ o o o o o / \ . . . . . /
\ o o o o / \ . . . . /
--------- ---------
Each pin has a number assigned to it. When connecting null modem, for
example, it is important to know these numbers in order to select the correct
cables, or when making your own cables.
DB-25 Connector
Chart #1 (Female)
13 <------- 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 /
-------------------------
25 <----- 14
Hi there, as far as I am concerned it is very difficult to make
your own printer cable and anyways they are cheap and easy to find in a store
down there on the street. REMEMBER I AM NOT ANY TECHNO-WIZARD. So don't ask me
details of each pins. You can email your problems regarding this section to the
author of the chart mentioned below. But, I am giving the collection of data
transmission of most common cables for everybody's reference. Following is the
chart for transmission of Data via Parallel Port.
Chart#13 Pin Assignments of Parallel Port
(LPT1) Female DB-25 on PC
<= in or => out
DB25 Pin
Cent Pin
Name of Signal
Reg Bit
Function Notes
=> out
1
1
-Strobe
C0-
Set Low p1ulse >0.5 us to send
=> out
2
2
Data 0
D0
Set to least significant data
=> out
3
3
Data 1
D1
...
=> out
4
4
Data 2
D2
...
=> out
5
5
Data 3
D3
...
=> out
6
6
Data 4
D4
...
=> out
7
7
Data 5
D5
...
=> out
8
8
Data 6
D6
...
=> out
9
9
Data 7
D7
Set to most significant data
<= in
10
10
-Ack
S6+
IRQ; Low Pulse ~ 5 uS, after accept
<= in
11
11
+Busy
S7-
High for Busy/Offline/Error
<= in
12
12
+PaperEnd
S5+
High for out of paper
<= in
13
13
+SelectIn
S4+
High for printer selected
=> out
14
14
-AutoFd
C1-
Set Low to autofeed one line
<= in
15
32
-Error
S3+
Low for Error/Offline/PaperEnd
=> out
16
31
-Init
C2+
Set Low pulse > 50uS to init
=> out
17
36
-Select
C3-
Set Low to select printer
==
18-25
19-30, 33,17,16
Ground
-
Do not connect any of these grounds to a
shield
Imp. Note: Some cables, ports, or connectors may not connect
all grounds. Centronics pins 19-30 and 33 are "twisted pair return" grounds,
while 17 is "chassis ground" and 16 is "logic ground".
"<= In" and
"=> Out" are defined from the viewpoint of the PC, not the printer. The IRQ
line (-Ack/S6+) is positive edge triggered, but only enabled if C4 is
1.
6B. IOMEGA ZIP DRIVE Parallel Port Cable Pinouts (Straight-through
PP Cable)
Most of the The External Parallel Port devices like IOMEGA ZIPDRIVE
uses Straight-through Parallel Port cable with Straight pinouts like 1 to
1, 2 to 2, 3 to 3 and so on upto 25 to 25. Though I may not be sure about
other Parallel Port Devices like External CDROM drives, you can give it a
try for other units on your own risk.
Laplink cable is used to link two PCs with MSDOS 6.0 or later, very
effectievly by using INTERSVR.EXE (on Host) and INTERLNK.EXE (on GUEST) PCs.
Laplink cable is also successfully used by me to link two PCs for only
FILE TRANSFER (not playing Games), with WIN95 and Direct Cable Connection
program with common protocol as "NETBEUI" on both Computerīs Network Section of
Control Panel. In Network section you must have installed "Client for Microsoft
Networks", "File and Printer Sharing for Microsoft Networks" and one more
protocol other than TCP/IP, that is "NetBEUI". Both the options in "File
and Print Sharing" button should be selected (checked) to allow all users to
access files and printer.
Then one computer must be as HOST mode and the other should be as GUEST mode.
Also only two computers can be connected to each other for only FILE TRANSFER
and not for anything else. The Rest is explained in HELP and Troubleshooting
Section of WIN95 itself. PLEASE DO NOT EMAIL FOR THE DCC OF WIN95/98 FOR THIS,
BELIEVE ME YOU WILL FIND THE BETTER INFO IN HELP OF WIN9x or try my FAQ
page for more info.
If you are seeking to buy a Parralel port Laplink cable, or trying to make
your own cable, you should know what pins need to be switched in order to make
it. Below is a chart of what pins go to what on the other end. Only 18 pins are
used in a Laplink Cable, therefore I will only show those eighteen here.
To make this cable we need 1. TWO numbers of DB-25 Male Sockets. 2.
Shielded Cable with 18 cores (lines of wires).
Chart#5
DCC Parallel Laplink Cable Pinouts.
Male DB-25
==>>
Male DB-25
1
Both Not used
2
to
15
3
to
13
4
to
12
5
to
10
6
to
11
7
Both Not used
8
Both Not used
9
Both Not used
10
to
5
11
to
6
12
to
4
13
to
3
14
Both Not used
15
to
2
16
Both Not used
17
to
19
18
to
18
19
to
17
20
Both Not used
21
to
21
22
to
22
23
to
23
24
Both Not used
25
to
25
Pinbody*
to
Pinbody
* = In my cable one
wire was attached to the metal body of the Male pins on both sides. Total 18
wired cable is necessary for this cable including one wire for Body of the pin
too.
IMP: On above information, I was congratulated by Don Schuman of http://www.lpt.com/, Parallel Technologies, the
inventors/developers of the parallel version of the Windows 95/98/2000 Direct
Cable Connection (DCC) feature and drivers. He has offered us a small nicely
animated software, DirectParallel Connection Monitor
Utility, for all the DCC users to troubleshoot and test DCC connection and
cable on both the computers. It also provides detailed information about the
connection, the cable being used for the connection, the I/O mode (4-bit, 8-bit,
ECP), the parallel port types, I/O address, and IRQ. The company, Parallel
Technologies, is associated with the Microsoft for DCC and can be seen listed in
Win9x Help (Index+Direct Cable Connection+ordering cables).
SPEED: Parralel port Laplink cable is always faster than Serial port
Cable because of more numbers of cores of wires used in Parallel port cable (25
pin) than Serial port Cable (9 pins). The expected speed is 300kb/second but it
is extremely dependent on the different quality chipset structure of Parallel
Ports on different makes of the Motherboards. Some even reported me the lowest
speed of 60kb/sec even though all other settings are correct. Its recommended
that you setup LPT1 mode as only "ECP/EPP" or "ECP" mode in bios to get better
speed, and not the "Normal" (4bit/8bit) modes.
For more Faster transfer of Files over DCC between PCS, you can think
of using UNIVERSAL FAST
CABLE by Parallel Technologies. You
will be stunned at its amazing features.
7B. NULL-MODEM cable for DCC file transfer?
Yes! About a DCC of Win9x
thru Serial Port a very important information I am going to put over.
Please read carefully. We can also use Null-modem cable to use with DCC
for Data transfer on Serial port with all above settings identical as we
use for DCC with Laplink Cable on Printer Port. The source of the info is
http://www.kime.net/directcc/directcc95.htm.
Please do not get confused with DTE and DCE descriptions on that site as
DTE is DB9 or DB25 MALE pin as found on system and DCE is DB9 or DB25
Female socket/pin as found on Modems. We usually get MALE DB9 or DB25 pin
serial ports on our computers which can also be called DTE type port. So,
just Enjoy. Next section is how to build your own Null-Modem
cable.
For making Null modem cable following is a chart of pinout. Only 8 pins are
used in a null modem, though there are 25 pins on DB-25 socket. You need 8 or
9-wired cable with two DB-25-Female pin socket or DB-9-Female pin socket or one
of both.
IMPORTANT : Both pin sockets must be of FEMALE type.
This may not be applicable on some machines, so please check your serial ports
of both the machines as there must be MALE pins at back of
your both computers.
Chart #6
Chart #7
Chart #8
Null-Modem Pinouts DB-25 to DB-25
2
to
3
3
to
2
4
to
5
5
to
4
6 and 8
to
20
7
to
7
20
to
6 and 8
Null-Modem Pinouts DB-9 to DB-9
1 and 6
to
4
2
to
3
3
to
2
4
to
1 and 6
5
to
5
7
to
8
8
to
7
Null-Modem Pinouts DB-25 to DB-9
2
to
2
3
to
3
4
to
8
5
to
7
6 and 8
to
4
7
to
5
20
to
6 and
1
Now why this cable is called null modem without using the modem?
by
grimace (grimace@xnet.com) That's good question. But if you think a little bit,
you will get an answer that as we don't use modem and use modem-like connection
on two computers staying together, so we call it Null-Modem Connection.
Most important is, as you may know that modem have its own data-transmission
method and special combination of the data input-output is required to be
configured to each pin of the modem cable so the special modem to computer cable
is used. But if you give more attention on CHART#11 and CHART#12 of my page you
will get an idea that how actual the DATA-TRANSMISSION takes place. Now if we
want to play multiplayer game from remote areas we need to connect systems with
MODEMS as follows...
MODEM GAME PLAY A's Computer ###### A's MODEM ------> TELEPHONE
CO.----->B's MODEM ###### B's Computer
In above (1st) diagram '######' is the cable which connects the Computer to
MODEM. The one which comes with modem.
NULL MODEM GAME PLAY A's Computer =================== B's Computer
In this (2nd) diagram '===========' resembles the null modem cable emulating
the 1st transmission. Now in above method the Null modem Cable's pinouts are
adjusted in such a way that it emulates the modem connection to the same
DATA-TRANSMISSION as MODEM to Computer connection requires. See chart#9 and #10.
Therefore it is called Null-Modem cable. Hope I could explain you the whole
saga.
IMPORTANT : Both pin sockets must be of DIFFERNT type.
This means that for modem-side of cable we need to use MALE
type of DB-25 pin. And on CPU side of cable we need to use FEMALE type of DB-25 or DB-9 pin.
Chart #9
Chart #10
Normal-Modem Pinouts DB-25 to DB-25
2
to
2
3
to
3
4
to
4
5
to
5
6
to
6
7
to
7
8
to
8
20
to
20
22
to
22
PinBody*
to
Pinbody*
Normal-Modem Pinouts DB-25 to DB-9
2
to
3
3
to
2
4
to
7
5
to
8
6
to
6
7
to
5
8
to
1
20
to
4
22
to
9
PinBody*
to
Pinbody*
*
Pinbody is OPTIONAL. We easily get cable with 9-wires in it, but not 10 then
Pinbody can be attached with shielded wire. The one which I examined from a
reputed company was having body of pins connected with shileded wire (let's
assume earthing line.)
The pin-configuration of internal serial cables (the one that
connects from the motherboard to the case) are different for different
motherboards, which come in two types. One with straight pins as in old mobos
like 286/386/486. And another is twisted style cable like in latest pentiums.
The MALE DB9 pin is connected to serial port on motherboard with 9 wired cable
in following two types. Both Serial ports on motherboard have 10 wires but only
9 of them to connect to MALE DB9 Serial Pins. Please do not connect 10th core
anywhere.
Chart# 14
DB9 Pinouts of STRAIGHT SERIAL PORT on 286/386
systems
Cable Wire number on motherboard
Wire Connected to male DB9 pin on cabinet.
1 Red Wire
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
Chart# 15
DB9 Pinouts of TWISTED TYPE SERIAL PORT on
modern systems
Cable Wire number on motherboard
Wire Connected to male DB9 pin on cabinet.
1 Red Wire
1
2
6
3
2
4
7
5
3
6
8
7
4
8
9
9
5
The MALE DB-25 pin is connected to serial port on motherboard with 9 wired
cable (Yes, 9-wired cable) in following two types. Both Serial ports on
motherboard have 10 wires to connect to MALE DB25 Serial Pins as follows. Take
it.
Chart# 16
DB25 Pinouts of STRAIGHT SERIAL PORT on
286/386 systems
Cable Wire number on motherboard
Wire Connected to male DB25 pin on cabinet.
1 Red Wire
8
2
3
3
2
4
20
5
7
6
6
7
4
8
5
9
22
Chart# 17
DB25 Pinouts of TWISTED TYPE SERIAL PORT on
modern systems
Cable Wire number on motherboard
Wire Connected to male DB25 pin on cabinet.
1 Red Wire
8
2
6
3
3
4
4
5
2
6
5
7
20
8
22
9
7
NOTE: The 10th Core
Wire from motherboard is an Optional line which can be connected to pin 1 of
DB25 with no harm.
IMP: Above are the exact pinouts of the all four types of working serial
ports with me for IBM Machines. Believe me, they should work. Please see
Chart#11 and Chart#12 in Section 5 of this page for pin-Descriptions of DB9 and
DB25 Serial ports.
Date: wed, 24 Sep 1997 19:51:38 +0100 From: "Jesse Eissens"
(jeissens@bigfoot.com) To: (mahendra@geocities.com) CONTENT : Whould you
happen to have the pinout for a 15 pin monitor connector? I have a Compaq and I
can't use the volume control on my monitor with my new Stealth 3D card. The
volume is controled by the mother board from the monitor to the sound card. I'd
like to make a patch cable to fix this problem. I can't seem to get the answer I
want from Compaq.
WARNING : THESE PINOUTS ARE OF THOSE CABLES WHICH I USED SUCCESSFULLY, THEN
OPENED AND EXAMINED BY ME FOR YOU. BUT PLEASE USE THIS INFO AT YOUR OWN RISK AND
DON'T HOLD RESPONSIBLE TO ME IF YOU MESS IT UP. NOBODY IS PERFECT SO NEITHER I.
Anyways as suggested by one of the visitor, Rodolfo Ortega Paredes mailto:sagat@writeme.com who successfully
prepared the null modem pinouts like others, I want to proudly state in his own
words that "The soldering of the cable is up to you, this information has no
errors."
Please read the website carefully and only if you have something extra
to ask then email me with your requests, changes, questions, corrections by
specifying Chapter Numbers and Diagram Numbers. Thanks for visiting. vbmcomputers@yahoo.com
This page hosted by Get your own Free Home Page
since Dec
1997.
8. IBM Null-Modem pinouts. (DB-25 to DB-25), (DB-9 to DB-9) and (DB-25 to DB-9).
9. IBM Normal Modem (Cable) pinouts. (DB-25 to DB-25) and (DB-25 to DB-9).
10.The pin-configuration of Internal Serial Cables inside Cabinet.
