4 Features and Functions
152 Keysight 34970A/34972A User’s Guide
– 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, be sure to
configure the scaling values first. 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 remove a channel from the scan list (by selecting CHANNEL OFF from
the front panel or by redefining the scan list from the remote interface), alarms
are no longer evaluated on that channel (during a scan) but the limit values are
not cleared. If you decide to add that 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.