HP 34970A See, page, Alarms, always, starting on, for more information, “The SCPI Status System,”, For complete details, refer to

Chapter 4 Features and Functions

Alarm Limits

∙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.

Alarm Event No Alarm

Upper Limit

Lower Limit

∙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 128.

∙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.

∙In addition to being stored in reading memory, alarms are also recorded in their own SCPI status system. You can configure the instrument to use the status system to generate a Service Request (SRQ) when alarms are generated. See “The SCPI Status System,” starting on page 275 for more information.

∙The default values for the upper and lower alarm limits are “0”.

The lower limit must always be less than or equal to the upper limit, even if you are using only one of the limits.

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