User`s guide

141
Chapter 4 Features and Functions
Alarm Limits
4
• Alarms are logged in the alarm queue only when a reading crosses a
limit, not while it remains outside the limit and not when it returns
to within limits.
• Four TTL alarm outputs are available on the rear-panel Alarms
connector. You can use these hardware outputs to trigger external
alarm lights, sirens, or send a TTL pulse to your control system. You
can also initiate a scan sweep (no external wiring required) when an
alarm event is logged on a channel. For complete details, refer to
“Using the Alarm Output Lines” on page 145.
• The following table shows the different combinations of front-panel
annunciators that may appear while using alarms.
An alarm is enabled on the displayed channel.
The indicated HI or LO limit is being configured on the indicated alarm (shown
while in the Alarm menu).
An alarm has occurred on one or more channels. The behavior of the alarm
output lines tracks the alarm annunciators on the front panel.
The alarm output lines have been cleared but alarms remain in the queue.
Alarm Event No Alarm
Upper Limit
Lower Limit
34970A Refresh UG.book Page 141 Wednesday, February 17, 2010 12:34 PM