ISDN S0 bus wiring configurations   
                       =================================

            Version 1.0  last edit-date: [Tue Oct 17 11:49:29 2000]


   Copyright (c) 2000 Hellmuth Michaelis. All rights reserved.

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Legend:

+--+
|TR| = Terminating resistor pair, each 100 Ohm +-5% >= 0,1W
+--+

+--+
|NT| = Network Terminator (to exchange)
+--+

+--+
|TE| = Terminal equipment (ISDN Telephone, ISDN PC card, etc.)
+--+


1 short passive bus (NT at the end, recommended)
------------------------------------------------------


       |                      D1                          |
       |<------------------------------------------------>|
       |                                                  |

   +--+                                                    +--+  +--+
   |TR|-----+------------------+-----------------+---------|TR|--|NT|
   +--+     |    ^             |                 |         +--+  +--+
            |    | D2          |                 |
            |    v             |                 |
           +--+ ---           +--+              +--+
            |TE|               |TE|              |TE|
           +--+               +--+              +--+


Maximum 12 Jacks
Maximum of 8 TE's
D1 = 100m max (cable impedance 75 ohms)
D1 = 200m max (cable impedance 150 ohms)
D2 = 10m max

The terminating resistor pair at the NT side is usually located inside
the NT.


2 short passive bus (NT at any point between the TR's)
------------------------------------------------------


       |                      D1                          |
       |<------------------------------------------------>|
       |                                                  |
                     +--+
                     |NT|
                     +--+
                      |
   +--+               |                                    +--+
   |TR|-----+---------+--------+-----------------+---------|TR|
   +--+     |    ^             |                 |         +--+
            |    | D2          |                 |
            |    v             |                 |
           +--+               +--+              +--+
           |TE|               |TE|              |TE|
           +--+               +--+              +--+


Maximum 12 Jacks
Maximum of 8 TE's
D1 = 100m max (cable impedance 75 ohms)
D1 = 200m max (cable impedance 150 ohms)
D2 = 10m max

The terminating resistors have to be switched off inside the NT.

3 extended passive bus
----------------------


       |                      D1                          |
       |<------------------------------------------------>|
       |                                                  |
            |   D3   |
            |<------>|
            |        |
   +--+                                                    +--+  +--+
   |TR|-----+--------+--------+----------------------------|TR|--|NT|
   +--+     |  ^     |        |                            +--+  +--+
            |  | D2  |        |
            |  v     |        |
           +--+     +--+     +--+
           |TE|     |TE|     |TE|
           +--+     +--+     +--+


Maximum 12 Jacks
Maximum of 8 TE's
D1 = 100m - 1000m max
D2 = 10m max
D3 = 25-50m

4 point to point
----------------


             |                      D1                       |
             |<--------------------------------------------->|
             |                                               |

   +--+  +--+                                                 +--+  +--+
   |TE|--|TR|-------------------------------------------------|TR|--|NT|
   +--+  +--+                                                 +--+  +--+


D1 = up to 1000m


5 contact assignments
---------------------

                                /           / /
                               /           / /
3 RX+ 2a --[100 Ohms]----+     ---------- / /    ----------
4 TX+ 1a --[100 Ohms]--+ |    | 87654321 | /    | 12345678 |
5 TX- 1b --------------+ |    |__      __|/     |/_      /_|
6 RX- 2b ----------------+       |____|            |/___|

                               RJ-45 Plug        RJ-45 Jack



Sources:
========

ITU I.430 (03/93) Annex A
http://www.adelheid.demon.co.uk/isdnwire.html
http://www.rz.uni-frankfurt.de/netz/isdn/s0-bus.html
http://me.in-berlin.de/~scorpio/faqkabel.html
http://www.kabelfaq.de/
http://www.belwue.de/anschluss/schulen/hilfestellungen/ulm/faq/misc/s0_bus12.htm
http://www.telekom.de/dtag/faq/download/isdn-hb/isdn-hb.pdf
http://me.in-berlin.de/~scorpio/isdnkabelfaq.txt