Appendix A
HMI Function Reference
©
National Instruments Corporation
A-7
Read Alarm Summary
Use the Read Alarm Summary VI to display current alarm information for a set of tags or tag
groups within a given alarm priority range. You also can filter out acknowledged alarms. This
VI formats the alarm summary information for display in an Alarm Summary Display in your
HMI. If you specify a timeout value greater than 0, this VI returns when the current alarm
information changes, or the timeout value is exceeded, whichever occurs first. The changed?
output alerts you as to whether the current alarm information has changed.
The format and color codes inputs determine how to format and color code summary
information. The Read Alarm Summary VI returns all the information needed to update the
Alarm Summary Display in your HMI. Part of the table indicator formatting is done through
attribute nodes which only can exist in your diagram. The column headers display the table
column header information and must be wired to your table Column Headers[] attribute if you
are displaying column headers. This is updated when the VI is executed for the first time, or
if you change the format during program operation. The initialize headers output is TRUE
when you need to update the column headers attribute.
You should wire the summary data output directly to your Alarm Summary Display. Wire
the row colors output to the Active Cell and Cell FG Color attributes inside of a While Loop.
Wiring the Alarm Summary Display attributes like this formats the table to show different
line colors for different alarm states. If you use the HMI G Wizard, this code is generated for
you automatically.
The entire Alarm Summary Display, including attributes, is updated only if the current alarm
information changes, and if there was no timeout. Table indicator updates can be slow for
large tables, so it is a good idea to update the table only if changed? is TRUE. Notice that
changed? is always TRUE after the first execution of the VI.
read parameters is a cluster of parameters for filtering out the alarms read.
min priority is the minimum priority of alarms to read. If left
unwired, alarms corresponding to priority level 1 and above are
reported.
