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Diagnostic Functions
The loopback point is always placed so that all channel circuitry is included in the loopback path.
If the data origin and loopback point are the same (a local loopback), data is looped back at the
interface between the channel and the MEGAMUX PLUS common cards. If the data origin and
the loopback point are different (an end-to-end loopback), data is looped back at the interface be-
tween the channel and the channel equipment. A loopback with data origin and loopback point at
the same node verifies the operation of the channel at that node only. A loopback with data origin
and loopback point at opposite nodes verifies the channels at either end and common equipment
between them, as well as the communication link between MEGAMUX PLUS units. (No chan-
nels are tested other than the one specified in test selection.)
Follow these steps to initiate the data path tests (except for voice channels):
1.
If you are using external test equipment (User Data Test) connect the test equipment to the
originating channel interface.
2.
Select the Channel diagnostics from the Diagnostics Functions Menu. Remember that you
must specify the channel by name or number, as described earlier in paragraph 5.0.
3.
Using the cursor position keys and the Return key, select the Data Path Tests from the chan-
nel Diagnostics Menu.
4.
When the Data Path Test display appears, the cursor is positioned at TEST TYPE. Use the
up and down cursor position keys to step through the possible tests (BERT, BERT with
clamp, User Data) until the desired test is displayed.
5.
Use the left and right cursor position keys to move the cursor to the DATA ORIGIN or
LOOPBACK POINT fields. Use the up and down cursor position keys to alternate between
Node M and Node S for data origin or loopback point.
6.
When the desired data origin and loopback point have been selected, press the Return key
to initiate the test. If you are using external test equipment, set the equipment to begin gen-
erating test data. The channel Diagnostics Menu returns to the screen, and the channel sta-
tus scan reports the test. If' a BERT test is running, the error count is displayed in the status
scan.
7.
To terminate the test, select Data Path Tests from the Diagnostic Menu. When the Data Path
Test display appears, select STOP TEST and then depress the return key. The status scan
indicates that the test is no longer in effect. (If desired, you may go directly to another test,
without terminating the existing test; the existing test is automatically ended by the system
when you select another test.)
8-11
036R660-000, Issue 10
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