EtherLite Cable Guide

RJ-45 Cabling/Pinouts

RS-422/485 Implementation

RS-232 Definitions

Connectors and Pinouts

RJ-45 Cabling/Pinouts

Important: The EtherLite RJ-45 8-pin configuration is not compatible with the pin configuration of the RJ-45 (usually 10-pin) connectors on all other Digi products. You must get or make the correct cables (shown below) for the EtherLite products to work as expected. Pre-configured cables for EtherLite products are available via Digi Sales. Be sure to get the correct cables when ordering.

RS-422/485 Implementation

RS-485 Multidrop

Only "4 wire" Master/Slave configurations are supported since the buffers are always enabled EtherLite products. In other words, transmit (TxD) pair is connected to all the slave device's receive (RxD) pairs, and the chain of slaves all have their TxD pairs connected to EtherLite and arbitrate normally for the "right to talk". In this configuration, the EtherLite termination switch should only be enabled (down position) if the EtherLite unit is at the end of the chain.

RS-422 Point-to-point

Termination is enabled when the termination switch is in the down position. RS-422 is enabled when the termination switch is in the up position. This puts a 120 Ohm 1/2 Watt resistor across the receive pair.

Notes

RS-232 Definitions

Signal

Description

TxD

Transmit Data

An output for DTE devices and an input for DCE devices. This is the data channel from the DTE device to the DCE device.

RxD

Receive Data:

An input for DTE devices and an output for DCE devices. This is the data channel from the DCE device to the DTE device.

RTS

Request To Send:

An output for DTE devices and an input for DCE devices. This signal is typically used to gate flow from the DCE device to the DTE device. In other words, the workstation serial port would drop this signal to halt flow from the modem, and then later raise it to resume flow.

CTS

Clear To Send:

An input for DTE devices and an output for DCE devices. This signal typically is used to gate flow from the DTE device to the DCE device. In other words, a modem may drop this signal to halt flow from the workstation, and then later raise it to resume flow.

DSR

Data Set Ready:

An input for DTE devices and an output for DCE devices. This signal is not widely used in UNIX, except on some DEC machines, which will block on open if it is not true in some cases.

GND

Signal Ground:

The signal return for all signal lines.

DCD

Data Carrier Detect:

An input for DTE devices and an output for DCE devices. This signal is used to show that there is a valid connection between the DTE and DCE devices. It is typically used to block opens on a port before connections, and to generate UNIX "hang up" signals upon loss of a connection.

DTR

Data Terminal Ready:

An output for DTE devices and an input for DCE devices. This signal is typically used in UNIX to show that the port has been activated or "opened".

Connectors and Pinout Information

DTE to DTE Null Modem Pinouts
Sample DTE to DTE "null-modem" wirings
Null-Modem Diagrams

DB-25 Connector

EtherLite products use the standard DTE pinout for DB-25 connectors, but female connectors are used to avoid possible pin shorts.

The following connector is used for products such as ST-1616, ST-1002, and ST-1008.

                             +--------------------------+
                              | 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    |
                              +--------------------------+

DB-9 (PC-AT-style) Connector
                           +--------------------------+
                            | pin | signal | direction |
  Male AT-style DB-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     |
                            +--------------------------+


RJ-45 Connectors

Digi uses its 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 similar to the ones used on the Digi units) is shown below with pin numbering.

This connector is used with products such as the Digi EtherLite products.

RS-422/485 Connector
                           +--------------------------+
    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:
                 .---------------------.
                  | CD RJ-45 | Terminal |
                  |----------+----------|
                  | RxD- (2) | TxD- (?) |
                  | RxD+ (4) | TxD+ (?) |
                  | TxD- (7) | RxD- (?) |
                  | TxD+ (5) | RxD+ (?) |
                  `---------------------'

RS-485 Connector (EtherLite 2 only)
                 +------------------------------------+
                  |RJ-45|              |               |
                  | pin |    Signal    |   Direction   |
                  |------------------------------------|
                  |  1  |  No connect* |               |
                  |  2  |  No connect* |               |
                  |  3  |  No connect* |               |
                  |  4  |  TX(A)RX(A)  | Bidirectional |
                  |  5  |  TX(B)RX(B)  | Bidirectional |
                  |  6  |  GND         |               |
                  |  7  |  No connect* |               |
                  |  8  |  No connect* |               |
                  +------------------------------------+
                  *Do not connect any signal.

Note:

RS-232 Connector
                           +--------------------------+
    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 Digi RJ45, and DB-25 or DB-9 connectors. These charts may also be used to configure any kind of adapter between EtherLite  RJ-45, a DB-25, or a DB-9 connections, but you may need to reorganize the data. It may help to draw your own "map" before committing the pins in your connector.

                         +-----------------------------------+
                          | RJ-45 |  RS-232   || DB-25 | DB-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 actually converting signals between different connectors.  No signal crosswiring is taking place.

                         
                          +---------------------------------------------+
                          | RJ-45 |  RJ-45    ||   DST*   |DB-25 | DB-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, use this        |   5   | TxD (out) || RxD (in) |  3   |  2   |
configuration.            |   6   | GND (n/a) || GND (n/a)|  7   |  5   |
                          |   7   | DTR (out) || DCD (in) |  8   |  1   |
                          |   8   | CTS (in)  || RTS (out)|  4   |  7   |
                          +---------------------------------------------+

Notes:

Full-handshaking Null-modem Connector

(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:

No-handshaking Null-modem Connector

(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:

Possible Printer Null-modem Connector

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 diagram can be used:

(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: