Ethernet Transceiver Cable

Figure 1 shows the standard 15-pin AUI connector signal assignments. The standard 10Base-T (RJ-45 jack) connector signal assignments are shown in Figure 2.

Figure 1 - Ethernet 15-Pin AUI Connector Assignments

RJ-45 Wiring Considerations

You should give special consideration to the wiring scheme when connecting a device such as a terminal to a MAXserver serial port. The MAXserver is considered a DTE device. If you want to connect to another DTE device such as a terminal that is also DTE, you will need a crossover wiring scheme somewhere in the cabling. (Communication between DTE-to-DTE devices requires a crossover.) When a DCE device is connected to a MAXserver serial port, straight-through wiring is required.

To make a modular cable with a crossover, you need only crimp the RJ-45 connector in the same direction at both ends. This crosses all wires in the cable. To make a modular straight-through cable, you need only crimp the RJ-45 connector in opposite directions at both ends. Figure 3 shows the crossover and straight-through wiring schemes.

The crossover connects the MAXserver transmit data (XMT) line to the receive data (RCV) line of the user DTE device. Similarly, the MAXserver receive data (RCV) line crosses over to the transmit data (XMT) line of the user DTE device. The other signals are crossed over in a similar manner.

Making Your Own RJ-45 Cables

If you make your own cables, you should be very careful when using the crimping tool. Make sure that the RJ-45 connector is fully inserted into the die set cavity of the crimping tool, and that the wire is fully inserted into the RJ-45 connector, before crimping. The die set might be fragile, and could break if the RJ-45 connector is not properly seated before you squeeze the handle.

Also, NBase-Xyplex recommends that you use different colored wires for straight-through and crossover cables, in order to keep track of the cable type. For example, Xyplex recommends silver wire for making crossover cables and black wire for making straight-through cables.

Modular Adapters:

You can obtain adapters from Xyplex which will direct signals from the RJ-45 connector on the cable to the correct pin on the DB-25, DB-9, or MMJ connector. To make your own adapters, though, use the appropriate pinouts as shown in the diagrams of the following three sections.

RJ-45 to DB-25

Figures 4 and 5 show how devices are cabled when using the RJ-45 to DB-25 adapters. Figure 6 shows the RJ-45 and DB-25 pin assignments.

Figure 4 - Adapter Wiring, RJ-45 to DB-25, MAXserver to DTE

Figure 5 - Adapter Wiring, RJ-45 to DB-25, MAXserver to DCE

NOTE: In order to expand the functionality of the serial interface, the MAXserver modular cabling allows you to connect different signals to pin 7 of the MAXserver. (This pin is an input to the MAXserver.) When a DCE device is connected to a MAXserver serial port, the device's DCD output is connected to pin 7. In this case, the signal at pin 7 is referred to as DCD.

When a DTE device is connected to a MAXserver serial port, the device's DTR output is connected to pin 7 of the MAXserver. In this case, the signal at pin 7 is referred to as DSR. (This cabling scheme also provides DECconnect compatibility, since DECconnect does not support the DCD signal.)

DEConnect to RJ-45 Cables

Figure 8 shows how the DEConnect cables are wired. The Male RJ-45 connector is attached to the MAXserver. The MMJ connector attaches to the DEConnect-compatible device (DTE). The cable is a crossover cable that uses the six inner pins of the server port and makes the signals available at the MMJ connector. The cable is constructed using standard six-wire cable.

Figure 8 - MAXserver DEConnect Cable

NOTE: If you have existing DEConnect cables that you want to use with the MAXserver, the one-foot straight through cable and the RJ-45 to MMJ adapter or modular adapter allow you to use these cables without making any changes. You can also use the male RJ-45 to female MMJ adapter.

MAXserver Technical Specifications