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097-55501-01 Revision M – January 2009
TimeHub 5500 User’s Guide 207
Chapter 5 Maintaining the TimeHub 5500
Clearing Output Port Alarms
Other than the possible alarm reporting, a measurement made with such a
connection remains as valid as it would otherwise have been. While such a
connection cannot be used in any case to evaluate output signal characteristics
such as mask compliance or amplitude levels (because the connection scheme is
inherently improper due to direct connection of a signal line ground), it is an
acceptable method for basic signal checking such as signal presence. Even though
TimeHub may report a port alarm, the TimeHub output signal will still be generated.
Also, this connection method will not damage the TimeHub output circuits.
So, while it is acceptable to directly connect as described previously (for limited
types of tests), the recommended method for connecting from differential to
single-ended is via a transformer, as is expected when connection is made to the
equipment that will ultimately be timed by the output. With this type of connection,
reporting of false port alarms should not occur.
Clearing False Port Alarms
A false port alarm will normally self-clear when the reason for its occurrence is
removed. For example, if a TimeHub ring output connected to test equipment
ground is the reason for a false port alarm, removing that connection typically clears
the alarm within a few seconds. If the alarm does not self-clear, use the CLRPTALL
keyword to request an attempt to clear the alarm (see the
TL1 Reference Guide
,
keyword CLRPTALL).
Using TimeScan THC software, the clear attempt can be activated via the following
sequence:
1. Select the
Configuration Output
tab (
) and identify the output card
group that is to have port alarm clear attempted. In the example shown, the
C
output group on the Master shelf is selected.
2. Select the
Service
,
Port Alarm Clear...
menu. A dialog box similar to
appears.