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colognechip edited this page May 22, 2017 · 1 revision

ISDN S0 cross connector

if you connect both RX/TX with termination, you have an looping cross connector.

   3 RX+ 2a ---+--------+          /           / /
   4 TX+ 1a --/         |          ---------- / /
                    [100 Ohm]     | 87654321 | /
   5 TX- 1b ----+       |         |__      __|/
   6 RX- 2b -----\------+            |____|

If you but this one you your HFC based ISDN TA and open the device using NT mode, you get every single frame send out to line interface immediately looped back to RX fifos.

ATTENTION: This connector will directly short-circuit your NT lines, so never use that connector with power-feeding NTs unless you like it hot...

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