Agilent Technologies 34970A, User Manual, Page: 139 / 356

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Chapter 4 Features and Functions
Alarm Limits
4
Alarm Limits
The instrument has four alarms which you can configure to alert you
when a reading exceeds specified limits on a channel during a scan. You
can assign a high limit, a low limit, or both to any configured channel in
the scan list. You can assign multiple channels to any of the four
available alarms (numbered 1 through 4). For example, you can
configure the instrument to generate an alarm on the Alarm 1 output
when a limit is exceeded on any of channels 103, 205, or 320.
You can also assign alarms to channels on the multifunction module. For
example, you can generate an alarm when a specific bit pattern or bit
pattern change is detected on a digital input channel or when a specific
count is reached on a totalizer channel. With the multifunction module,
the channels
do not have to be part of the scan list to generate an alarm.
For complete details, see “Using Alarms With the Multifunction Module”
on page 148.
Alarm data can be stored in one of two locations depending on whether a
scan is running when the alarm occurs.
1. If an alarm event occurs on a channel as it is being scanned, that
channel’s alarm status is stored in reading memory as the readings
are taken. Each reading outside the specified alarm limits is logged in
memory. You can store up to 50,000 readings in memory during a
scan. You can read the contents of reading memory at any time, even
during a scan. Reading memory
is not cleared when you read it.
2. As alarm events are generated, they are also logged in an alarm
queue , separate from reading memory. This is the only place where
non-scanned alarms get logged (alarms during a monitor, alarms
generated by the multifunction module, etc.). Up to 20 alarms can be
logged in the alarm queue. If more than 20 alarm events are
generated, only the first 20 alarms are saved). Even if the alarm
queue is full, the alarm status is still stored in reading memory
during a scan. The alarm queue is cleared by the
*CLS
(clear status)
command, when power is cycled, and by reading all of the entries. A
Factory Reset (
*RST
command) does not clear the alarm queue.
34970A Refresh UG.book Page 139 Wednesday, February 17, 2010 12:34 PM