Csu Loop - Patton electronics 2701/B User Manual

Figure 8. Remote Loop in a Network Extension Application
There are two Remote Loops that can be initiated from the NetLink-E1
unit: (1) V.54 Loop, and; (2) CSU Loop. The user can select the type of
loop that can be initiated by Switch S2-4. When a loopback is initiated
this is the type of loop that the unit uses to loop up the remote unit and
which type of loop the unit will respond to.
To perform an RDL test, follow these steps:
1. Activate RDL. This may be done in two ways:
— Activate the "RL" signal on the DTE (2701/B and 2701/C only). If
you are not sure which lead is the "RL" signal, please refer to
Appendix B or C, depending on the version you are using.
— Set the front panel switch to "Remote".
2. Perform a bit error rate test (BERT) using the internal V.52 genera-
tor (as described in section "Using the V.52 (BER) Test Pattern
Generator"), or using a separate BER Tester. If the BER test indi-
cates a fault, and the Local Line Loopback test was successful for
both NetLink devices, you may have a problem with the twisted
pair line connection.

CSU Loop

Although CSU Loop is predominantly a T1 function, the NetLink-2701
responds to central ofÞce initiated loop commands. Customers can use
this facility when the Central OfÞce network switch supports CSU loops
over an E1 interface.
When CSU Loop is selected, the NetLink 2701 will implement the "loop
up" command when it recognizes the pattern "10000" in the data stream
for a minimum of 5 seconds. The "loop down" command is implemented
by the pattern "100" in the data stream for a minimum of 5 seconds.
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