| Serial |
Network |
| MMJ |
RJ-45 |
| DB-9 |
DB-15
(AUI) |
| DB-25 |
DB-9
Token Ring |
| RJ-45 |
V.35 (X.25) |
| MMJ |
RJ-45 |
DB-9 Female |
DB-25 Female |
DB-25 Male |
|
| MMJ |
See |
See |
See |
See |
|
| DB-9 Male |
Intermec 9154 |
||||
| RJ-45 |
See |
Network
Straight-Through Network Crossover FDDI Crossover DECserver to Cisco Router |
See Flowpoint Router Alcatel-Lucent router 7750 with Cisco 3500 switch |
See |
The following colors are standard. If your cable doesn't have these, you're on your own.
Blue
White / Blue
Green
White / Green
Brown
White / Brown
Orange
White / Orange
MMJ Cable
The standard MMJ cable has six wires, and is flat, not round.
DB-9
and DB-25 Connectors
DB-9's and DB-25's (at least the ones you buy at Radio Shack) have
little numbers beside each hole. If yours don't have numbers,
here's the key. These views are from the back of the connector.
Female Male
------------- -------------
\ 1 2 3 4 5 / \ 5 4 3 2 1 /
\ 6 7 8 9 / \ 9 8 7 6 /
--------- ---------
Other DB connectors use the same scheme.
DB-15
Connector
DB-15 connectors are used as network connectors known as as AUI or MAU
ports. Older systems referred to them as ThickWire Ethernet ports,
since the old vampire taps used them. They are still widely seen
on equipment, and transceiver modules are available to convert them to
10Base-T (RJ-45) networks. One such module is the CentreCOM
210TS.
RJ-45,
RJ-11, and MMJ Connectors
How are those phone-style plugs (RJ-45, MMJ) numbered?
Look into the socket. Twist around so that the little plastic clip is pointing down (towards your chin). The leftmost position is 1.
When you insert wire into a plug, make sure the clip is down.
Holding the connector so that it's pointing away from you, the leftmost
position is 1.
DB-25 and DB-9
The worldwide standard (sort of) is the DB-25. Everyone calls
this RS-232, but that name's been replaced by an EIA number that nobody
uses. Warning: There are lots of pins in a DB-25
that are used for all sorts of obscure functions. Don't assume
that "no connection" means "no function".
Male connectors are usually used on PC's. Female connectors are usually used on modems. Usually.
Here's what the commonly used pins mean in a DB-25:
1 GND
(Protective ground, almost never used)
2 TXD
(Transmit data)
3 RXD
(Receive data)
4 RTS
(Request to send)
5 CTS
(Cleared to send)
6 DSR (Data
Set ready)
7 GND
(signal ground)
8 DCD (Data
carrier detect)
20 DTR (Data
terminal ready)
22 RI (Ring
indicator)
DB-9's are simpler. They are not used for weird stuff (usually). The DB-9 "standard" was developed by IBM because they wanted to save money -- DB-25's are bigger, and so more expensive. Here are the pinouts:
1 DCD
(Data carrier detect)
2 RXD
(Receive data)
3 TXD
(Transmit data)
4 DTR (Data
terminal ready)
5 GND
(Signal ground)
6 DSR (Data
set ready)
7 RTS
(Request to send)
8 CTS
(Cleared to send)
9 RI
(Ring indicator)
Note: The pinouts for early MicroVAX systems do not follow this scheme. See
the VMS FAQ
for details.
Warning: Token Ring networks also use DB-9's, but are definitely not serial!
RJ-45 -- Serial
Lots of equipment uses RJ-45's for serial connections. They're
cheaper than DB-25's and DB-9's, and are a lot easier to mount on a
panel. Here are the pinouts for the DECserver series of terminal
servers. DEC called this the "MJ8" connector. Your mileage
may vary with other devices.
1 RX-
(Receive ground)
2 RX+
(Receive data)
3 RX-
(Transmit ground)
4 CTS
(Cleared to send)
5 RTS
(Request to send)
6 TX
(Transmit data)
7 DTR (Data
terminal ready)
8 DSR (Data
set ready)
Note that the transmit and receive data are actually differential
line drive, instead of voltages. This is known as EIA-423.
Cisco routers have a different scheme (thanks to Jim Azbell):
1 RTS
(Request to send)
2 DTR (Data
terminal ready)
3 TXD
(Transmit data)
4 GND
(Signal ground)
5 GND
(Signal ground)
6 RXD
(Receive data)
7 DSR (Data
set ready)
8 CTS
(Cleared to send)
Note that these lines are driven against ground, not
differential like the DECservers. The Cisco
documentation says that pins 1 and 8 are connected in their
standard cable.
1 RX
(Receive data)
2 RTS (Request to
send)
3 N/C (no
connection)
4 TX
(Transmit data)
5 GND (Ground)
6 CTS (Cleared to
send)
7 N/C (no
connection)
8 N/C (no
connection)
Here's an Alcatel-Lucent router 7750 with
Cisco 3500 switch, provided by Sergio Antonio. I haven't tested
this combination.
RJ-45 DB-9
1
RTS 8 CTS
2
N/C 6 DSR
3
TxD 2 RxD
4 GND 5 GND
5
GND 5 GND
6
RxD 3 TxD
7
N/C 4 DTR
8
CTS 7 RTS
RJ-45 -- 10Base-T
RJ-45's are also used for network connections. The most common
10Base-T scheme is known as TIA/EIA T568B, which is:
Pin Function
1 Receive
2 Receive
3 Transmit
4 unused
5 unused
6 Transmit
7 unused
8 unused
There are applications specified for ISDN, analog voice, IEEE 802.5/Token Ring, and other stuff. I found a useful information in OPEN DECconnect System Overview, figure 2-2 and table 2-3.
DB-15 -- Ethernet
The AUI (MAU, ThickWire) DB-15 connectors have the following
pinouts. (This is from a document that used to be on the Ericsson
web site)
The DEC Ethernet loopback connector 12-22196-02 has the
following connections (from the DECstation
5000 hardware guide)
Pins 3 and 5
Connected through a capacitor
Pins 10 and 12 Connected through a
capacitor
Pins 13 and 6 Connected through a
resistor and LED
DB-9 -- Token-Ring
The AUI (MAU, ThickWire) DB-15
connectors have the following pinouts. (This is from a document
that
used to be on the Ericsson web site)
DEC Adapters
There are all sorts of useful adapter modules that were made by
Digital Equipment Corporation. The wiring
diagrams are here. A table of them are
in the VMS FAQ.
MMJ
Digital created the MMJ connector. You can recognize it because
the plastic clip is not in the center. It was a great idea -- the
connections are simple, but no one else adopted the idea. The
pinouts:
1 DTR
(Data terminal ready)
2 TX+
(Transmit data)
3 TX-
(Transmit ground)
4 RX-
(Receive ground)
5 RX+
(Receive data)
6 DSR (Data
set ready)
MMJ's use differential drive, just like RJ-45's. Funny enough, the RJ-45 to MMJ cable is the hardest to build...
MMJ ends and crimpers are hard to find. After hours of
searching, I found that Ideal Industries sells them. The crimper
is product 30-497, and a bag of 100 MMJ ends for round cable (Cat 5 is
round) is product 86-393. I got mine at Michaels Electrical
Supply
(http://www.michaelselectric.com).
Costs about $100 total.
CABLES
Now, how do you make it play? I have actually tested most of
these configurations. All you need is a large spool of Cat 5
wire,
appropriate crimpers and ends, and endless time. Enjoy!
10Base-T straight through
cable
The "straight through" cable is used to connect a network device (LAN
card, etc.) to a hub or switch. This cable has TIA/EIA T568B
connectors on each end (hey, they look like RJ-45's to me!). Each
connector is wired like this:
Pin Wire
1 White / orange
2 Orange
3 White / green
4 Blue
5 White / blue
6 Green
7 White / brown
8 Brown
10Base-T crossover cable
This cable is used to connect two identical devices. You can
connect two LAN cards together to create a miniature network. Or
you can connect two hubs together to expand your network.
Technically, one connector is TIA/EIA T568B, and the other is TIA/EIA
T568A. Take a look:
Connector 1 Connector
2
Pin Wire
Pin Wire
1 White /
orange
1 White / green
2
Orange
2 Green
3 White /
green
3 White / orange
4
Blue
4 Blue
5 White /
blue
5 White / blue
6
Green
6 Orange
7 White /
brown
7 White / brown
8
Brown
8 Brown
When I make one of these, I use a red Sharpie marker and put a band
near each end so I won't confuse it with a straight through
cable.
Your mileage may vary.
FDDI crossover cable
Wait, I thought FDDI used fiber! Well, yes, but there's a version
of FDDI that uses UTP -- which is good old Cat 5 cable with
RJ-45's. It's also known as CDDI, or "FDDI over copper".
The
only reason you'd need a crossover cable is because you're connecting
two FDDI cards together. I had to do this, so just in case you
need to know:
Connector 1 Connector
2
Pin Wire
Function Pin Wire
1 White /
orange
Tx+
1 White / brown
2
Orange
Tx-
2 Brown
3 White /
green
3 White / green
4
Blue
4 Blue
5 White /
blue
5 White / blue
6
Green
6 Green
7 White /
brown
Rx+
7 White / orange
8
Brown
Rx-
8 Orange
The colors used here are not standardized as they are for
10Base-T. I just used the 10Base-T standard for the first
connector. FDDI requires that the outside two pairs are swapped,
but the other pairs are straight through. The good thing about
standards is there are so many to choose from!
MMJ to MMJ
It seems every piece of Digital equipment has at least one MMJ
connector. Here's how to make a "straight through" MMJ
cable. The colors are my own choice.
1
Orange
1 White / orange
2
Blue
2 Green
3 White /
blue 3 White / green
4 White /
green 4 White / blue
5
Green
5 Blue
6 White /
orange 6 Orange
There's no "crossover" MMJ cable -- all MMJ cables are "straight
through". I said that it was a simpler idea.
RJ-45 to DB-9 Female
This hooks a PC's serial port to a DEC terminal server. I left
out the "handshaking" lines (RTS, CTS, DSR, DTR, DCD, RI).
RJ-45
DB-9 Female
1 White /
blue
1 No connection
2
Blue
2 Green
3 White /
green
3 Blue
4
Brown
4 No connection
5 White /
brown
5 White / green and White / blue
6
Green
6 No connection
7 White /
orange 7 No
connection
8
Orange
8 No connection
9 No connection
Digital made an adapter, H8585-AA, with the following pinouts. Could this be the full-handshaking version of the above? I haven't tested it, but it would seem likely.
RJ-45
DB-9 Female
1 White /
blue
1 Connect to pin 6 and White / orange
2
Blue
2 Green
3 White /
green
3 Blue
4
Brown
4 Orange
5 White /
brown
5 White / green and White / blue
6
Green
6 Connect to pin 1 and White / orange
7 White /
orange 7
Brown
8
Orange
8 White / brown
9 No connection
RJ-45 to DB-25 Male
This hooks a DEC terminal server to a modem. The handshaking
lines are used in this one. Unfortunately, there's no place on a
RJ-45 for DCD or RI. Digital made an adapter for this called the
H8585-AC.
RJ-45
DB-25 Male
1 White /
blue 2 Green
2
Blue
3 Blue
3 White /
green 4 White / brown
4
Brown
5 Brown
5 White /
brown 6 Orange
6
Green
7 White / green and White / blue
7 White /
orange 20 White / orange
8 Orange
Digital's DECserver 900TM could be configured to bring those signals out on the RJ-45 instead of DSR and CTS. They made an adapter, the H8585-AB, which had these pinouts:
RJ-45
DB-25 Male
1 White /
blue
2 Green
2
Blue
3 Blue
3 White /
green
7 White / green and White / blue
4
Brown
8 Orange
5 White /
brown 20
White / orange
6
Green
22 Brown
7 White /
orange 23 White /
brown
8 Orange
RJ-45 to MMJ
This is probably the hardest cable to make. That's because both
of these are crimp-on connectors. First, the pinouts:
RJ-45
MMJ
1 White /
blue 1 Orange and
brown
2
Blue
2 Blue
3 White /
green 3 White / blue
4
Brown
4 White / green
5 White /
brown 5 Green
6
Green
6 White / orange
7 White / orange
8 Orange
See how the first wire in the MMJ needs to connect to two wires on the RJ-45? What I do is cut off about 2 inches of the outer cover on the cable near the MMJ end (before I put on the MMJ!). I cut off the White/brown wire (it doesn't go to the MMJ), and strip all the insulation off the Brown wire. I then carefully (very carefully) strip about 1/2 inch of insulation off the Orange wire. If you do this right, the Orange wire's insulation just slips up. I then wrap the two wires together. I put the outer insulation back on, less about 1/2 inch. A piece of electrical tape makes it secure. I then put on the MMJ as indicated.
Digital's BN24H cable was similar to the above, but without the brown wire being hooked to pin 1 of the MMJ.
Digital did make an adapter, the H8584-AC, with the following pinouts. This is a RJ-45 plug and MMJ socket.
RJ-45
MMJ Socket
1 White /
blue
1
White / orange
2
Blue
2 Green
3 White /
green 3
White / green
4
Brown
4 White / blue
5 White /
brown 5 Blue
6
Green
6 Orange and brown
7 White / orange
8 Orange
RJ-45 (DECserver) to RJ-45 (Cisco
router)
To connect a Cisco router's console port to a DECserver terminal server
(thanks to Jim Azbell):
RJ-45
(DECserver) RJ-45
(Cisco)
1 White /
blue
1
Brown
2
Blue
2 Orange
3 White /
green 3 Blue
4
Brown
4 White / blue
5 White /
brown 5
White / green
6
Green
6 Green
7 White /
orange 7 White /
orange
8
Orange
8 White / brown
RJ-45 (FlowPoint) to DB-9 Female
To connect a FlowPoint router's console port to a PC's serial port
(from http://support.efficient.com/docs/pdf/Techrefguide.pdf):
RJ-45
DB-9
1 White /
blue
1
no connection
2
Blue
2 White / blue
3 White /
green 3
Brown
4
Brown
4 no connection
5 White /
brown 5
White / brown
6
Green
6 no connection
7 White /
orange 7 Blue
8
Orange
8 Green
9 no connection
MMJ to DB-25 Female
This hooks an older PC's serial port to a Digital MMJ device (such as a
VT220 terminal). Digital made an adapter called a H8575-A with
these pinouts:
MMJ
DB-25 Female
1
Orange
2 Blue
2
Blue
3 Green
3 White /
blue
4 Connect to pin 5
4 White /
green
5 Connect to pin 4
5
Green
6 Connect to pin 8 and White / orange
6 White /
orange 7
White / blue and White / green
8 White / orange and pin 6
20 Orange
MMJ to DB-9 Female
This hooks a PC's serial port to a Digital MMJ device (such as a VT220
terminal). Digital made an adapter called a H8571-J with these
pinouts:
MMJ
DB-9 Female
1
Orange
1 Connect to pins 6 and 8 and White / orange
2
Blue
2 Green
3 White /
blue 3 Blue
4 White /
green 4 Orange
5
Green
5 White / blue and White / green
6 White /
orange 6 Connect to
pins
1 and 8 and White / orange
7 No connection
8 Connect to pins 1 and 6 and White / orange
9 No connection
Note: The pinouts for early MicroVAX systems do not follow this scheme. See
the VMS FAQ
for details.
DB-9 Male
(Intermec) to DB-9 Female
This hooks a PC's serial port to an Intermec 9154 scanner's management
port. This is Intermec cable number 060728-00028.
DB-9
Male
DB-9 Female
1 No
connection
1 White / blue
2
Blue
2 Green
3
Green
3 Blue
4 No
connection
4 No connection
5 Orange
5 White / green
6 No
connection
6 No connection
7 White / green
7 No
connection
8 No
connection
8 Orange
9 White / blue
9 No connection
The AirBorn page in Australia has some good stuff: http://www.airborn.com.au/rs232.html
The VMS FAQ
has lots of good info.
This DEC cable manual is handy: Cable-guide.html
NullModem.com has lots of pinouts
More
DECconnect adapters are here:
http://www.lammertbies.nl/comm/cable/dec-mmj.html
B&B Electronics makes some good devices, and has lots of reference materials.
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