HP 34970A manual Alarm System Overview

Chapter 5 Remote Interface Reference

Alarm System Overview

∙You can assign an alarm to any configured channel and multiple channels can be assigned to the same alarm number. However, you cannot assign alarms on a specific channel to more than one alarm number.

∙When an alarm occurs, the instrument stores relevant information about the alarm in the queue. This includes the reading that caused the alarm, the time of day and date of the alarm, and the channel number on which the alarm occurred. The information stored in the alarm queue is always in absolute time format and is not affected by the FORMat:READing:TIME:TYPE command setting.

∙You must configure the channel (function, transducer type, etc.) before setting any alarm limits. If you change the measurement configuration, alarms are turned off and the limit values are cleared. Alarms are also turned off when you change the temperature probe type, temperature units, or disable the internal DMM.

∙If you plan to use alarms on a channel which will also use scaling,

wz “”z v” z “. If you attempt to assign the alarm limits first, the instrument will turn off alarms and clear the limit values when you enable scaling on that channel. If you specify a custom measurement label with scaling, it is automatically used when alarms are logged on that channel.

∙If you redefine the scan list, alarms are no longer evaluated on those

channels (during a scan) but the limit values vz cleared. If you decide to add a channel back to the scan list (without changing the function), the original limit values are restored and alarms are turned back on. This makes it easy to temporarily remove a channel from the scan list without entering the alarm values again.

∙Each time you start a new scan, the instrument clears all readings (including alarm data) stored in reading memory from the previous scan. Therefore, the contents of reading memory are always from the most recent scan.

∙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.

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