Paradyne ACCULINK 316x - Manual (Page 123)

Maintenance
4-7 3160-A2-GB22-10 December 1996
Starting a Payload Loopback
The Payload Loopback command (PLB) loops the
received signal on the network interface back to the
network. The signal is looped back as close to the DSX-1
Drop/Insert port (DTE) as possible (after it has passed
through the framing circuitry of the DSU/CSU).
Therefore, framing CRCs and BPVs are corrected. If bit
stuffing is enabled, pulse density is enforced.
To perform a Payload loopback,
1. Press F2 to select Test from the top-level menu
screen.
F1
DSU ESF
Stat
Test Cnfig
F2 F3
2. From the Test screen, press F2 to select Lpbk.
F1
Test:
Rlpbk Lpbk
Ptrns
F2 F3
3. From the Loopback screen, press F3 to select
PLB.
F1
Loopback:
Abort
LLB PLB
F2 F3
Test Started appears on Line 2. If a Payload
loopback is already in progress, the Already
Active message appears. If an invalid combination
of loopbacks is in progress, the error message
Invalid Test Combo appears (see Table 4-2 for
valid loopback test combinations).
Starting a DTE Loopback
The DTE Loopback command (DLB) loops the
received signal on the DSX-1 Drop/Insert port (DTE)
back to the DTE without change.
A DTE loopback can be activated and deactivated
based on the state of an external contact on the DSX-1
Drop/Insert port (DTE). If this option is enabled with the
DTE Interface configuration option Extrn DLB, closing
the contact (relay contact sense and relay contact return)
activates a DLB. The DLB remains active until the
contact is opened. Refer to the DSX-1 Port DTE Interface
section in Appendix D, Pin Assignments, for more
information.