This connector is used products such as our ST-1616, ST-1002, and ST-1008 products.
+--------------------------+
| pin | signal | direction |
Female DB-25 DTE |--------------------------|
| 2 | TxD | out |
___________ | 3 | RxD | in |
( 13......1 ) | 4 | RTS | out |
\ 25...14 / | 5 | CTS | in |
`-------' | 6 | DSR | in |
| 7 | GND | n/a |
| 8 | DCD | in |
| 20 | DTR | out |
+--------------------------+
+--------------------------+
| pin | signal | direction |
Male AT-style DE-9 DTE |--------------------------|
| 1 | DCD | in |
___________ | 2 | RxD | in |
( 1.......5 ) | 3 | TxD | out |
\ 6.....9 / | 4 | DTR | out |
`-------' | 5 | GND | n/a |
| 6 | DSR | in |
| 7 | RTS | out |
| 8 | CTS | in |
| 9 | RI | in |
+--------------------------+
We use our own RJ-45 pin configuration, which is noted where appropriate below. To avoid confusion, an ASCII representation of an RJ-45 receptacle (the female connector like the ones used on our units) is shown below with pin numbering.
This connector is used products such as our EtherLite products, PCI products, and also most of our SCSI products.
+--------------------------+
1 2 3 4 5 6 7 8 | | RS-422 | |
.--+-+-+-+-+-+-+-+--. | pin | signal | direction |
| | | | | | | | | | |--------------------------|
| R- R+T+ T- | | 1 | RTS * | out |
| | | 2 | RxD- | in |
| | | 3 | DCD * | in |
| | | 4 | RxD+ | in |
| | | 5 | TxD+ | out |
'-----. .-----' | 6 | GND * | n/a |
|_ _| | 7 | TxD- | out |
| | | 8 | CTS * | in |
'---' +--------------------------+
Notes:
- * These signals are always RS-232 (single-ended) even when the
port is set to "RS-422 mode".
- For point-to-point connections, such as directly to a single terminal,
you should use the following connection method:
.---------------------.
| CD RJ-45 | Terminal |
|----------+----------|
| RxD- (2) | TxD- (?) |
| RxD+ (4) | TxD+ (?) |
| TxD- (7) | RxD- (?) |
| TxD+ (5) | RxD+ (?) |
`---------------------'
+--------------------------+
1 2 3 4 5 6 7 8 | | RS-232 | |
.--+-+-+-+-+-+-+-+--. | pin | signal | direction |
| | | | | | | | | | |--------------------------|
| | | 1 | RTS | out |
| | | 2 | DSR | in |
| | | 3 | DCD | in |
| | | 4 | RxD | in |
| | | 5 | TxD | out |
'-----. .-----' | 6 | GND | n/a |
|_ _| | 7 | DTR | out |
| | | 8 | CTS | in |
'---' +--------------------------+
Here are a few sample wiring configurations to help configure cables when
adapting between OUR RJ45, and DB-25 or DE-9 connectors. You could
also use the charts below to configure any kind of adapter between our
RJ-45, a DB-25, or a DE-9, but you may need to reorganize the data a bit.
It may help to draw your own "map" before comitting the pins in your
adapter.
+-----------------------------------+
| RJ-45 | RS-232 || DB-25 | DE-9 |
The standard DTE adapter: | pin | signal || pin | pin |
------------------------- |-------------------||--------------|
To make an adapter that | 1 | RTS (out) || 4 | 7 |
would simply give you | 2 | DSR (in) || 6 | 6 |
a standard DTE DB-25 | 3 | DCD (in) || 8 | 1 |
for direct connect with | 4 | RxD (in) || 3 | 2 |
modems, use this | 5 | TxD (out) || 2 | 3 |
configuration. | 6 | GND (n/a) || 7 | 5 |
| 7 | DTR (out) || 20 | 4 |
| 8 | CTS (in) || 5 | 8 |
+-----------------------------------+
NOTE: The above "adapter" is really more of a "converter", as we're
mainly just changing (converting) the our connector from an RJ-45
to a DB-25 or RJ-45. No signal "crosswiring" is taking place.
We're not changing our "identity" from DTE to DCE as we are in
the table below.
+---------------------------------------------+
| RJ-45 | RJ-45 || DST* |DB-25 | DE-9 |
The custom DCE adapter: | pin | signal || signal | pin | pin |
------------------------- |-------------------||------------------------|
To make an adapter that | 1 | RTS (out) || CTS (in) | 5 | 8 |
would allow you to | 2 | DSR (in) || ------ | n/c | n/c |
directly connect to | 3 | DCD (in) || DTR (out)| 20 | 4 |
terminals and most | 4 | RxD (in) || TxD (out)| 2 | 3 |
printers... ONLY, use | 5 | TxD (out) || RxD (in) | 3 | 2 |
this configuration. | 6 | GND (n/a) || GND (n/a)| 7 | 5 |
| 7 | DTR (out) || DCD (in) | 8 | 1 |
| 8 | CTS (in) || RTS (out)| 4 | 7 |
+---------------------------------------------+
NOTE: * Above, DST refers to the signal on a normal DB-25 or DE-9 DTE
connector which would end up being connected to our RJ-45 signal
as a result of the above pinning. In other words, the first line
says that our RTS signal would be connected to the CTS signal of
a terminal (or other DTE device) with pin 1 at the RJ-45 connected
to pin 5 of a DB-25 shell or pin 8 of a DE-9 shell. Clear as mud?
Welcome to cabling!
NOTE: Make sure to use a STRAIGHT THROUGH (ONE-to-ONE) RJ-45 cable!
Most TELCO modular cables are flipped from end to end, and will
not work with our products. This means pin 1 is connected to pin
8, pin 2 to pin 7, etc.. Sometimes, the straight through cables
are also called data cables. Just make sure pin 1 at both ends
is on the same wire, as well as pin 2, etc..
NOTE: USE CAUTION WITH ETHERNET CABLES FOR RS-232 CONNECTIONS. Ethernet,
or category x (such as cat 5) cable has twisted pairs, and is not
designed for use with a single-ended interface such as RS-232.
If you use this type of cable with Central Data's connectors,
among other things, RxD (receive) and TxD (transmit) will be
twisted together, and be subject to crosstalk interference. The
net result is that reliability decreases as cable length and/or
baud rates increase, which is contrary to what one might assume
using "high quality" cable.
That being said, there is a way to use Cat 5 cable with modular
RS-232, but you have to do some special wiring. First, you have
to know which wires are twist pairs. One wire in each twisted
pair (of four total) MUST BE GROUND. This means you only have 4
actual RS-232 signals you can run, but it will be very reliable.
Most people opt to run RxD, TxD, DTR, and DCD. This does
everything except hardware flow control, which is fine for
terminals and serial printers, which are the most typical devices
to be at the other end of a long cable.
(DTE) (DTE)
----- -----
SG ----------- SG
TxD ----------- RxD
RxD ----------- TxD
RTS ----------- CTS
CTS ----------- RTS
DSR --+
DCD --+-------- DTR
GND ----------- GND
DTR --------+-- DSR
+-- DCD
Example pin connections:
------------------------
DB-25 -> DB-25 CD RJ-45 -> DB-25
-------------- -----------------
2 -> 3 TxD - RxD 5 -> 3
3 -> 2 RxD - TxD 4 -> 2
4 -> 5 RTS - CTS 1 -> 5
5 -> 4 CTS - RTS 8 -> 4
7 -> 7 GND - GND 6 -> 7
6+8 -> 20 DSR+DCD - DTR 3 -> 20 (DCD - DTR)
20 -> 6+8 DTR - DSR+DCD 7 -> 8 (DTR - DCD)
2 -> n/c or pin 6 (see note below)
Notes:
(DTE) (DTE)
----- -----
SG) ----------- SG
TxD ----------- RxD
RxD ----------- TxD
DCD --+ +-- DCD |
DSR --+ +-- DSR |- modem control loopback
DTR --+ +-- DTR |
GND ----------- GND
RTS --+ +-- CTS |
CTS --+ +-- RTS |- hardware flow control loopback
Example pin connections:
------------------------
DB-25 -> DB-25 CD RJ-45 -> DB-25
-------------- -----------------
2 -> 3 TxD - RxD 5 -> 3
3 -> 2 RxD - TxD 4 -> 2
6+8+20 DSR+DCD+DTR 2, 3, and 7 not connected. (see note below)
7 -> 7 GND - GND 6 -> 7
4+5 RTS+CTS 1 and 8 not connected. (see note below)
Notes:
Some terminals are designed to use DTR and CTS for hardware flow control instead of the more common RTS/CTS pairing. Some serial PRINTERS are also designed this way. In these cases, the following wiring makes the most sense:
(DTE) (Terminal/Printer)
----- ------------------
SG ------------- SG
TxD ------------- RxD
RxD ------------- TxD
RTS ------------- CTS
CTS ------------- DTR
GND ------------- GND
DSR --+
DCD --+
DTR --+
Example pin connections:
------------------------
DB-25 -> DB-25 CD RJ-45 -> DB-25
-------------- -----------------
2 -> 3 TxD - RxD 5 -> 3
3 -> 2 RxD - TxD 4 -> 2
4 -> 5 RTS - CTS 1 -> 5
5 -> 20 CTS - DTR 8 -> 20
7 -> 7 GND - GND 6 -> 7
6+8+20 -> n/c DSR+DCD+DTR 2 -> not connected. +
3 -> not connected. +-(see note below)
7 -> not connected. +
Notes:
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