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Chapter 9 Troubleshooting
Resolving problems
Datacom testing
110
Table 34
describes situations that you may encounter when performing
Datacom testing with the E1 Tester.
Table 35
Issues and resolutions
Issue
No receive clock
The receive clock is
inverted
The receive clock is
inverted
No pattern synchroni-
zation
No pattern synchroni-
zation
SmartClass E1 Tester User's Guide
Resolution
Check the Datacom settings. Specifically, make sure the
following settings are correct: Test Mode, Standard, Tim-
ing Mode, and DTE/DCE Rx Timing.
Check the adaptor cable:
– Make sure you are using the correct adaptor cable
for the interface standard and test mode.
– Make sure the adaptor cable is securely attached to
the E1 Tester.
Check the Datacom settings. Specifically, make sure the
RX Timing setting is correct. For higher speed DCE
emulation, terminal timing normally has to be used in
order to avoid clock/data phase issues.
Check the frequency of the circuit under test:
– The frequency should not exceed the specified max-
imum rate supported by the currently selected inter-
face standard.
– The maximum rate that can be supported will vary
depending on the selected standard and the timing
mode.
If additional cabling has been added to extend the
length of the test cable:
– Make sure the cable uses the proper shielding.
– Make sure the length is not too long for the speed of
the circuit under test.
Check the test pattern selection to ensure the correct
test pattern has been selected. For patterns with both
ANSI (North American) and ITU (European) versions,
ensure that the proper version has been selected.
Check the Tx and Rx Data Polarity settings to make
sure the proper TX and RX Data Polarity settings are
selected. Most applications use the default "Normal"
setting for both Tx and Rx Data Polarity.
– Perform a self test. See
page
61.
– Check the Rx Data Mark and Rx Data Space status
to ensure that data transitions are being received. If
a solid mark is being received, check the state of all
signaling leads to make sure the proper signaling
leads are being asserted. Frequently a DCE will not
allow data to proceed when it does not detect the
expected state on the DTE's signaling leads (DTR,
RTS).
Check the out of band flow control setting. If flow control
is on, a generator hold may be preventing the pattern
from being transmitted.
"Performing a self test" on
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