Csu Loopback; Dsu Loopback; Loopback; Local Loopbacks - Textron Greenlee Communications DataScout 10G User Manual

Users Manual 87
DataScout 10G & 10Gx

CSU Loopback

The test set detects reversal of sealing current and loops the receive circuit to the
transmit circuit. The CSU loopback code is detected by the OCU and the OCU revers-
es sealing current to the CSU/DSU. This loopback is used for checking wiring, OCU's,
DS0 and helps separate where the problem is at the demarc or Customer Premise
(CPE). Removal of sealing current or return to normal polarity terminates the CSU

loopback.

DSU Loopback

The test set detects the Alternating DSU loopback sequence and loops it's receive
back to transmit. The 'Misc. Status Message' line will display "DSU LOOPBACK". After
reception of four consecutive non-DSU loopback codes the DSU loopback is removed.
V.54 Loopback
The test set detects the latching V.54 loopback pattern and loops it's receive back to
transmit. The 'Misc. Status Message' line will display V.54 LOOPBACK. The test set
will loop down when a V.54 loop down sequence is received.

Local Loopbacks

Local loopbacks are helpful if the CO cannot loop the test set. To select local loop-
back, tap the loopback button and select CSU or DSU local loopback and then tap
loop-up. The test set will loop the receive signal to the transmit path. To loop down
tap the loopback button and then tap loop-down.
To loop a far-end CSU/DSU use the "All data V.54" loopback. This loopback does not
have any control codes and will not be remapped by the DDS elements. V.54 loop-
backs are great for end-to-end tests if the far-end CSU/DSU supports a V.54 loop-
back).