Cabling Guide for RJ-45 Console and AUX Ports

Types of RJ-45 Cabling

There are two types of RJ-45 cabling, straight and rolled. If you hold the two ends of an RJ-45 cable side by side, you'll see eight colored strips, or pins, at each end. If the order of the colored pins is the same at each end, then the cable is straight. If the order of the colors is reversed at each end, then the cable is rolled.

Note: CAB-OCTAL-ASYNC, the 8-port RJ-45 adapter that is used with the Cisco 2509, 2510, 2511, and 2512, is the same as a rolled cable.

Styles of RJ-45-to-DB25 Connectors

There are three styles of RJ-45-to-DB25 connectors, DCE style (modem), DTE style, and DCE style (non modem). Each one has a different role. Generally, DTE is for terminals, DCE (modem) is for modems, and DCE (non-modem) is obsolete.

Note: You can change a DCE style (non modem) to a DCE style (modem) by moving pin 6 to pin 8.

Setups That Work

You can't mix and match these components randomly. Only the following combinations will work:

RJ-45 DB25 TO ATTACH PORT: CABLE: STYLE: TO A: -------------------------------------------------- AUX/Console Rolled DTE TERMINAL AUX/Console Straight DCE non-modem TERMINAL AUX/Console Rolled DCE modem MODEM

These are the only setups that will work. If you don't have the components you need, use the chart below to order them.

RJ-45 Component Guide

This chart summarizes RJ-45 components. The first seven entries are DB25 connectors, and the last two are RJ-45 cables. Connectors are described in terms of their sex and their role. For example, an FDTE is a female DTE style connector, an MMOD is a male modem style connector, and so on. Remember, you need shielded cables in order to run at 115.2 Kbps.

STYLE CATALOG PART # CATALOG DESCRIPTION LABEL SHIELDED? ----- ----- -------------- ------------------- ------------------- --------- DTE CAB-25AS-FDTE= CABLE CONN-FTDTE 29-1026-01/TERMINAL yes DTE CAB-500DTF= DB-25 CONNECTOR, 29-0810-01/29-DTF-01 no DTE FEMALE DTE CAB-500DTM= DB-25 CONNECTOR, 29-0811-01/29-DTM-01 no DTE MALE modem CAB-25AS-MMOD= CABLE CONN-MODEM 74-0458-01/MODEM yes TO RJ45 SHLD modem CAB-MMOD= ADP,RJ45/DSUB 29-0881-01/29-MMOD-01 no DCE CAB-500DCF= DB-25 CONNECTOR, 29-0809-01/29-DCF-01 no (non modem) DCE FEMALE DCE CAB-500DCM= DB-25 CONNECTOR, 29-0808-01/29-DCM-01 no (non modem) DCE MALE NA Rolled Cable CABASY,RJ45 ROLLED, 72-0876-01/CAB-500RJ NA MODULAR NA Straight Cable -not in catalog- 31-0756-01 NA

RJ-45 Port Pinouts

This chart shows the pinouts for RJ-45 console and AUX ports. The console port does not use RTS/CTS.

Console/Auxiliary Port (DTE) ---------------------------- Pin Signal Input/Output ---------------------------- 1 RTS Output 2 DTR Output 3 TXD Output 4 GND - 5 GND - 6 RXD Input 7 DSR Input 8 CTS Input

RJ-45 Adapter Pinouts

This chart shows the pinouts for RJ-45 adapters.

Cable RJ-45 Pins DTE style DCE style DCE style (modem) (non modem) ------------------------------------------------ 1 4 5 5 2 20 8 6 3 2 3 3 4 7 7 7 5 7 7 7 6 3 2 2 7 6 20 20 8 5 4 4

This chart shows suggested DB-25 to DB-9 adapter pinouts, if you need a DB-9 connector.

DB-25 Pin Signal DB-9 Pin ----------------------------- 2 TXD 3 3 RXD 2 4 RTS 7 5 CTS 8 6 DSR 6 7 GND 5 8 DCD 1 20 DTR 4