Patton electronics 2720/I Series User Manual page 37

5.2.2 Operating Remote Digital Loopback (RL)
The Remote Digital Loopback (RL) test checks the performance of
both the local and remote NetLink-T1™, as well as the communication
link between them. Any characters sent to the remote NetLink-T1™ in
this test mode will be returned back to the originating device (i.e, char-
acters typed on the keyboard of the local terminal will appear on the
local terminal screen after having been passed to the remote NetLink-
T1™ and looped back).
T1/FT1 CSU/DSU
Ethernet
Device
Clock/
Data
Clock/
Data
There are two Remote Loops that can be initiated from the
NetLink-T1 unit: (1) V.54 Loop, and; (2) CSU Loop. The user can
select the type of loop that can be initiated from the System
Diagnostics/Statistics screen or with Switch S1-1. When a loopback
is initiated this is the type of loop that the unit uses to loop up the
remote unit. NOTE: The NetLink-T1 will respond to both loops regard-
less of the state of the RDL Type.
To perform an RDL test, follow these steps:
1. Activate RDL. This may be done in two ways:
a. Enter Remote Loop from the System
Diagnostics/Statistics menu and toggle the <Spacebar>
until "RL" appears next to the Remote Loop option.;
b. Set the front panel switch to 'Remote'.
2. Perform a bit error rate test (BERT) using the internal V.52
generator (as described in Section 5.3), or using a separate
BER Tester. If the BER test indicates a fault, and the Local
Line Loopback test was successful for both NetLink™s, you
may have a problem with the twisted pair line connection.
Model 2720/I
Internal
Clocking
Model 2720/I
RL Initiated
Figure 9. Remote Loopback
T1/FT1 CSU/DSU
Model 2720/I
Receive
Recover
Clocking
Cable Span
Data
Model 2720/I
36
Ethernet
Device
Clock/
Data
x
Data