Cat5 Cable Application Wiring HOWTO (Easy Plugs Lazydoc)


Some document I created in 2002 with some nice Ascii-Art.

Summary

In computer and telecom networks a variety of different interfaces exists. Instead of installing all sorts of different cables for these interfaces, it is more efficient to use 8-pin modular connector adaptor plugs for these interfaces and connect them with standard structured wiring Cat5 cables instead. This HOWTO explains how this can be done for the most frequently used interfaces.

Introduction

This document explains how to use structured wiring for various applications. For suggestions and feedback write to my email address .

Generic Cabling System Overview

The most widely used generic cabling structure for use in buildings is specified in European standard EN 50173, which is mostly equivalent to US standard EIA/TIA 568A. It covers campus 1st level interconnections between buildings, 2nd level interconnections between building distributor cabinets and floors, and 3rd level star topology connections from floor distributor cabinets to terminal adaptor outlets in the office area.

It is beyond of the scope of this document to go into details. It just needs to be noted here that for the 3rd level of wiring use of balanced copper wiring of certain quality is recommended. This results in:

  • Installed cable length 90 meters (295 feet) max.
  • Cat 5 compatible foil shielded twisted pair plenum cable with a characteristic impedance of 100 Ohms at 100 Mhz.
  • EIA/TIA 568A compliant wiring to shielded 8 position female modular connectors on both ends for installed cables.
  • Patch cable length max. 2 meters, 8 position male modular connectors on both ends.
  • 1:1 wiring, no crossover cables for application transparency.

Here is some of my favourite ASCII-art of a 8 position modular connector, also known as an RJ45 connector:

                     /  //
                    /  //
                   /  //
           _______/__//______
          /                 /|
         /                 / |
        /                 /  |
RJ45   /                 /   |
MC    /                 /    /
     / / / / / / / / / /    /
    / / / / / / / / / /    /
    | | | | | | | | | |   /
Pin | 8 7 6 5 4 3 2 1 |  /
    |                 | /
    |    +-------+    |/
     ----+       +----
         +-------+
            | |/
            +-+

Cat5 striped color codes are standardized. EIA 568A defines the pinout for Category 5 cable wires as follows:

MC-1  Pin 1  WHT-GRN (white/green)  -- pair 3
MC-2  Pin 2      GRN (green)        --/
MC-3  Pin 3  WHT-ORG (white/orange) ---------- pair 2
MC-4  Pin 4      BLU (blue)         -- pair 1  /
MC-5  Pin 5  WHT-BLU (white/blue)   --/       /
MC-6  Pin 6      ORG (orange)       ---------/
MC-7  Pin 7  WHT-BRN (white/brown)  -- pair 4
MC-8  Pin 8      BRN (brown)        --/

When using the MC-x Pin notation, this document always refers to 8 pin modular connectors. Note that the EIA/TIA 568B wiring scheme differs from 568A. It has green and orange pairs swapped. Use 568A compliant installation material only.

Applications Overview

The TIA 568A cabling structure is generic and sutiable to a wide variety of applications. Typical applications include connections for analog phones, ISDN S0 and S2M (E1/T1), 10/100/1000 Base-T (Ethernet), Token-Ring, CDDI and ATM (Asynchronous Transfer Mode). With some knowledge of the installed cable length, this also can be used for short inhouse serial asynchronous V.24/RS232 connections.

Adaptors

Most applications like twisted pair Ethernet use 8 pin modular connectors as its standard. They can be used directly with the structured wiring. For other applications such as RS232 (V.24, serial asynchronous communication), which use different connector types, adaptors must be used. There is no officially released standard for 8 pin modular adaptor plugs to my knowledge. The wires are in most cases connected to the modular female connector according to the following color scheme for solid colors:

MC-1  Pin 1  BLU (blue)
MC-2  Pin 2  ORG (orange)
MC-3  Pin 3  BLK (black)
MC-4  Pin 4  RED (red)
MC-5  Pin 5  GRN (green)
MC-6  Pin 6  YEL (yellow)
MC-7  Pin 7  BRN (brown)
MC-8  Pin 8  GRY (grey)

Make sure to double check this color scheme with the adaptor when configuring a new one.

Per Application Wire Usage

The following table compares some frequently used applications and their use of the wires of a Category 5 cable:

 ______________________________________________________________
|        |568A   |Solid|Analog|ISDN S0|ISDN     |10/100  |Magma|
|RJ45 Pin|Color  |Color|Phone |C7E1/T1|S2M      |Base-T  |V.24 |
|________|_______|_____|______|_______|_________|Ethernet|_____|
|1_______|wht-grn|blu__|______|_______|Rx_(tip)_|TD+_____|DCD__|
|2_______|grn____|org__|______|_______|Rx_(ring)|TD-_____|SG___|
|3_______|wht-org|blk__|______|2a_____|_________|RD+_____|DSR__|
|4_______|blu____|red__|a_____|1a_____|Tx_(tip)_|________|CTS__|
|5_______|wht-blu|grn__|b_____|1b_____|Tx(ring)_|________|DTR__|
|6_______|org____|yel__|______|2b_____|_________|RD-_____|RxD__|
|7_______|wht-brn|brn__|______|_______|+________|________|TxD__|
|8_______|brn____|gry__|______|_______|-________|________|RTS__|

More details regarding these applications can be found below. Note that the solid color to pinout assignment may vary and always must be double checked.

Device Types

Most applications have uni-directional data lines. This means, an output (electrical source) on one side gets connected to an input (electrical drain) on the other side. As all connections are wired straight through 1:1, the devices connected to each other are called data communication equipment (DCE) on one side and data termination equipment (DTE) on the other.

  • DCE Devices: Ethernet Hubs and Switches, Telephone Modems, ISDN Terminal Adaptors.
  • DTE Devices: Sun Workstations, Intel PC, ASCII Terminals.
  • DCE and DTE must be connected with straight (1:1) cables.
  • DTE-DTE or DCE-DCE device connections require crossover (Null Modem) cables.

Additionally, there are 2 types of electrical connections. This are either single ended connections or differential connections. In general, differential technology gets used as this is more robust and well suited for the 90 m cable length allowed by the standard. Only RS232/V.24 uses single ended connections, which in addition are not electrically isolated from ground. This requires special planning, see below.

Practice Tips

Keep application dependancies inside adaptor plugs, not cables. Don’t use crossover patch cables. They create application dependancy and jeopardize the idea of having a generic cabling infrastructure. It also makes error tracing a pain in large installations.

Applications

This chapter descrbes what is needed to connect certain devices using a Cat5 cable or cabling structure.

Ethernet LAN Connections

PC to Hub LAN Connection

Just a regular Cat5 patch cable!

PC to PC direct LAN Connection

Connect a patch cable to each PC and connect the 2 cable ends using an Ethernet X connector block. This crossover connector block can be built using 1 standard DB-9 Female MAGMA 1:1 connector (see below) and this special Ethernet crossover plug:

(TODO: base on DB9 adaptor, as this is smaller.) Connect for crossover: TD+ RJ45 1 to RD+ 3, TD- 2 to RD- 6, RD+ 3 to TD+ 1, RD- 6 to TD- 2.

 ----------------------
| RJ45-1 ------ DB25-6 | blue
| RJ45-2 ------ DB25-3 | orange
| RJ45-3 ------ DB25-8 | black
| RJ45-6 ------ DB25-7 | yellow
 ----------------------

Two Ethernet LANs on one Cat5 cable

2 Ethernet LANs may share one cable. The cable has to be terminated on each end with a T-Adaptor each according to this wiring diagram:

1 MC-1F ------------ MC-1M  1TD+
1 MC-2F ------------ MC-2M  1TD-
1 MC-3F ------------ MC-3M  1RD+
1 MC-4F           -- MC-4M  2TD-
1 MC-5F        - /-- MC-5M  2TD+
1 MC-6F ------/-/--- MC-6M  1RD-
1 MC-7F      / / --- MC-7M  2RD+
1 MC-8F     / / / -- MC-8M  2RD-
           / / / /
2 MC-1F --/ / / /
2 MC-2F ---/ / /
2 MC-3F ----/ /
2 MC-4F      /
2 MC-5F     /
2 MC-6F ---/
2 MC-7F
2 MC-8F

MC-xF means 8 pin modular female connector, MC-xM means male connector. There are T-Adaptors commercially available from Hubbell, order number BR851D.

Asynchronous RS232 Serial Connections

RS232 / V.24 is a single ended type interface, cable length may be up to 15m at speed up to 19.2 Kbit/sec. On some Sun systems the interface can be jumpered to current loop RS422. Standard connector for V.24 is a DB25 (25 pin). Connectors like DB9 (IBM PC style) are a de facto standard, but RJ45 pinouts vary a lot (Cisco, Magma etc.).

Note that V.24 is not isolated and therefore care must be taken when connecting devices which are hooked up to different AC power circuits. Use active opto- isolator plugs when connecting two devices. There are 2 abreviations for serial lines in use. We prefer the 3 character names.

TxD = TD = Transmit Data
RxD = RD = Receive Data
RTS = RS = Request to send
CTS = CS = Clear to send
DSR = DR = Data set ready
DCD = CD = Carrier Detect
DTR = TR = Data terminal ready
TxC = TC = Transmit data clock
RxC = RC = Receive data clock
XTC = XC = Clock

The input and outputs of a V.24 connector of a DTE device are as follows:

 ------------
| DTE Device |
| Sun        |
|            |
| DB25F  2 ----> TxD
| DB25F  3 <---- RxD
| DB25F  4 ----> RTS
| DB25F  5 <---- CTS
| DB25F  6 <---- DSR
| DB25F  7 ----- SG
| DB25F  8 <---- DCD
| DB25F 20 ----> DTR
|
| DB25F 15 <---- TxC
| DB25F 17 <---- RxC
| DB25F 24 ----> XTC
|            |
 ------------

The V.24 pin assignment for an IBM PC serial adapter port looks as follows (Pinout is not showing Ring Indicator on pin 9, as this is rarely used):

 ------------
| DTE Device |
| IBM PC     |
|            |
| DB9M   3 ----> TxD
| DB9M   2 <---- RxD
| DB9M   7 ----> RTS
| DB9M   8 <---- CTS
| DB9M   6 <---- DSR
| DB9M   5 ----- SG
| DB9M   1 <---- DCD
| DB9M   4 ----> DTR
|            |
 ------------

Pin layout of a DB9 Male connector is as follows:

                    / //
                ---/ //
               /  ---/
              /  //
    _________/__//__________
   /                       /|
  /                       / |
 /-----------------------/  |
|    ------------------  |  |
|   /-----------------/  |  |
|   \ /1 /2 /3 /4 /5 /   |  |
| *  \              /  * |  |
|     \ /6 /7 /8 /9/     | /
|      ------------      |/
 ------------------------/

The V.24 RJ45-connector of a MAGMA SBus card uses a pinout we also use as the starndard for transmitting RS232 via Cat5, as we found by testing, that this works quite well even with longer distances. Note: Ignore the RJ45 pin numbers shown in the Magma manual.

 --------
|  Magma |
|        |
| MC-7 ----> TxD
| MC-6 <---- RxD
| MC-8 ----> RTS
| MC-4 <---- CTS
| MC-3 <---- DSR
| MC-2 ----- SG
| MC-1 <---- DCD
| MC-5 ----> DTR
|        |
 --------

Basic idea for a collection of adaptors is to use RJ45 cables (Cat 5 patch cables, EIA/TIA 568 building wirings) and to keep a selection of various adapters that convert the variety of interfaces to the "standard Magma" interface.

Example 1: Connection of a Sun to a modem.

 ---  -----------------      cable     ----------------  -----
|Sun|| RS232/Magma 1:1 | o----------o |RS232/Magma 1:1 ||Modem|
 ---  -----------------                ----------------  -----

Example 2: Connection of 2 Sun Console Ports:

 ---  -----------------    cable   --------------------------  ---
|Sun|| RS232/Magma 1:1 | o------o |RS232/Magma Null Modem||Sun|
 ---  -----------------            --------------------------  ---

Schematic for connection of DTE to DTE device:

RxD <------ TxD
TxD ------> RxD
CTS <------ RTS
RTS ------> CTS
DTR ----+-> DSR
        +-> DCD
DSR <-+---- DTR
DCD <-+
SG  ------- SG

Schematic for connection of DCE to DCE device with DSR:

RxD ------> TxD
TxD <------ RxD
CTS ------> RTS
RTS <------ CTS
DTR <------ DSR
        --- DCD
DSR ------> DTR
DCD ---
SG  ------- SG

DB25 asynchronous 1:1 Adaptor

Adapter which connect to 25 pin interfaces can have either male or female DB25 connectors. Label the adapter as follows: 'RS232/Magma 1:1'. Internal wiring: brown ---- DB25-2 yellow ---- DB25-3 From white ---- DB25-4 Modular red ---- DB25-5 Connector black ---- DB25-6 orange ---- DB25-7 blue ---- DB25-8 green ---- DB25-20

DB 9 asynchronous 1:1 Adaptor

Adaptors for 9 pin PC style DB connectors mostly require DB9 female connectors only, as a PC (DTE) has a 9 pin male connector. Label the adapter as follows:

'RS232/Magma 1:1'.

                      / //
                  ---/ //
                 /  ---/
                /  //
    ___________/__//________
   /                       /|
  /                       / |
 /-----------------------/  |
|    ------------------  |  |
|   /-----------------/  |  |
|   \ O5 O4 O3 O2 O1 /   |  |
| *  \              /  * |  |
|     \ O9 O8 O7 O6/     | /
|      ------------      |/
 ------------------------/

Internal wiring:

           blue   ---- DB9-1
           yellow ---- DB9-2
           brown  ---- DB9-3
From       green  ---- DB9-4
Modular    orange ---- DB9-5
Connector  black  ---- DB9-6
           grey   ---- DB9-7
           red    ---- DB9-8
                  ---- DB9-9

DB9 DTE-DTE asynchronous Null Modem Adaptor

Label the adapter as follows: 'RS232/Magma DTE Null Modem'. Internal wiring:

           blue   ------.  .--- blue       DB9-1
           brown  ------|--|--- brown      DB9-2
           yellow ------|--|--- yellow     DB9-3
From       black  ------+--|--- black      DB9-4
Modular    orange ---------|--- orange     DB9-5
Connector  green  ---------+--- green+blue DB9-6
           red    ------------- red        DB9-7
           grey   ------------- grey       DB9-8
  DB9-9

DB9 DCE-DCE asynchronous Null Modem Adapter with DSR

Label the adapter as follows: 'RS232/Magma DCE Null Modem'. Internal wiring:

           blue   --         -- blue       DB9-1
           brown  ------------- brown      DB9-2
           yellow ------------- yellow     DB9-3
From       black  ------------- black      DB9-4
Modular    orange ------------- orange     DB9-5
Connector  green  ------------- green      DB9-6
           red    ------------- red        DB9-7
           grey   ------------- grey       DB9-8
  DB9-9

DB25 DTE-DTE asynchronous Null Modem Adaptor

Label the adapter as follows: 'RS232/Magma DTE Null Modem'. Internal wiring:

           yellow ------------- yellow     DB25-2
           brown  ------------- brown      DB25-3
           red    ------------- red        DB25-4
From       grey   ------------- grey       DB25-5
Modular    green  ----------+-- green+blue DB25-6
Connector  orange ----------|-- orange     DB25-7
           blue   ------.   .-- blue       DB25-8
           black  ------+------ black      DB25-20

DB25 DCE-DCE asynchronous Null Modem Adapter with_DSR

Label the adapter as follows: 'RS232/Magma DCE Null Modem'. Internal wiring:

           yellow ------------- yellow     DB25-2
           brown  ------------- brown      DB25-3
           red    ------------- red        DB25-4
From       grey   ------------- grey       DB25-5
Modular    green  ------------- green      DB25-6
Connector  orange ------------- orange     DB25-7
           blue   --         -- blue       DB25-8
           black  ------------- black      DB25-20

Other Vendor specific serial pinouts for modular connectors

Note that these pinouts are not compliant to the Magma pinout used.

V.24 RJ45-connector of a MOXAmod SBus card (DTE)

Moxa CN2000 Termnial Server. This devices uses a 10 pin RJ45 like connector. To be able to use regular Cat5 cables, the device has to be modified by connecting Pin 1 (of 10) to Pin 4 (of 10). Note: Ignore the MOXA Users Manual pinout description. Use the pinout naming convention below.

 ----------
|  MOXA    |
| 10 pin!  |
|          |
| MC10-1 ----- internally connected to MC10-4
| MC10-2 <---- DTR MC-1
| MC10-3 ----> CTS MC-2
| MC10-4 ----> DCD MC-3
| MC10-5 ----> RxD MC-4
| MC10-6 <---- TxD MC-5
| MC10-7 ----- SG  MC-6
| MC10-8 <---- RTS MC-7
| MC10-9 ----> DSR MC-8
| MC10-10 ----
|          |
 ----------
V.24 RJ45-connector of Cisco Router port (DTE)

Used for console and AUX. DCD is not being supported.

 --------
|  Cisco |
|        |
| MC-3 ----> TxD
| MC-6 <---- RxD
| MC-1 ----> RTS
| MC-8 <---- CTS
| MC-7 <---- DSR
| MC-4 ----- SG
| MC-5 ----- SG
| MC-2 ----> DTR
|       |
 -------

Analog Phone Connections

Just plug the RJ11/12 connector of the phone right into the middle of the 8 pin modular plug and do the same on the other end in the floor distributor. Cable length is no problem.

ISDN S0 Connections

ISDN S0 is a bus system and its overall lenght is about 1000m. What you can do is to install the ISDN NT inside the floor distributor, hook up a 1-to- 8 distribution box (wich is just a 9 modular femal connectors wired in parallel) and connect patch cables to that distribution box, or connect ISDN devices to it directly. (todo: add reference to standard)

ISDN S2M Connections

(todo: add reference to standard)