Verilink Productivity 500 (34-00236) Product Manual - Manual (Page 78)

Page 78 500 TA Test Mode Operation
after a call is placed successfully. The DTR Reset (&D3) option will not affect
this test mode.
Figure 9 Bilateral Loopback
To initiate the test, enter AT&T8 from the PC. The 500 TA can be online or
offline when the test is initiated but a call must be placed before the unit can
loop B-channel data. Any protocol, mode, and DTE rate can be used, however,
the protocol and DTE rates on the two units must be compatible. The remote
unit should be set to the same rate adaptation protocol as the local 500 TA and
left in normal data mode (NOT placed in Bilateral test mode). Data sent by the
remote TA will be received by the local 500 TA then echoed back to the remote
TA. The test is successful if the data is successfully echoed back to the sender.
A BERT device can be helpful in checking for data errors. Also, data from the
local PC will be echoed back to the PC. The PC portion of the test verifies the
operation of the PC, the PC cable, the PC interface to the 500 TA, and the data
buffers in the 500 TA.
The test should be run in both directions if possible (i.e. use the local 500 TA as
both the sending unit and as the loopback unit). If the B-channel data test is
successful, it indicates that the local and remote units and the network are func-
tioning. If there are errors, the problem could be in any of those elements.
The test is terminated by using the AT '+++' escape sequence to return to AT
command mode and then entering AT&T0.
ISDN
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Remote Unit
Local Unit
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