Agilent Technologies 34970A manual Using the Alarm Output Lines, Alarms Connector

Chapter 4 Features and Functions

Alarm Limits

Using the Alarm Output Lines

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 assign an alarm to any configured channel and multiple channels can be assigned to the same alarm number. Each alarm output line represents the logical “OR” of all channels assigned to that alarm number (an alarm on any of the associated channels will pulse the line).

Alarm 4 Output

Alarm 3 Output

Alarm 2 Output

Alarm 1 Output

or

Gnd

Alarms Connector

You can configure the behavior of the alarm output lines as described below. The behavior of the alarm annunciators on the front panel also tracks the alarm output configuration. The configuration that you select is used for all four alarm output lines. A Factory Reset (*RST command) clears all four alarm outputs but does not clear the alarm queue in either configuration.

•Latch Mode: In this mode, the corresponding output line is latched true when the first alarm occurs and remains asserted until you clear it by initiating a new scan or cycling power. You can manually clear the output lines at any time (even during a scan) and the alarm data in memory is not cleared (however, data is cleared when you initiate

a new scan).

•Track Mode: In this mode, the corresponding output line is asserted only when a reading crosses a limit and remains outside the limit. When a reading returns to within limits, the output line is automatically cleared. You can manually clear the output lines at any time (even during a scan) and the alarm data in memory is not cleared (however, data is cleared when you initiate a new scan). The alarm outputs are also cleared when you initiate a new scan.

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