Rockwell Automation FactoryTalk View Machine Edition Users Guide - Manual (Page 124)

F ACTORY T ALK V IEW M ACHINE E DITION U SER ’ S G UIDE
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Tags and expressions
Before setting up alarms, you must set up data server or HMI tags corresponding to the
addresses at the data source that will store the values you want to monitor for alarm
conditions. You can monitor analog and digital tags for alarm conditions, including both
HMI and data server tags. You cannot monitor string tags.
For information about setting up data server tags, see your OPC data server
documentation. For information about creating HMI tags, see Chapter 7.
You can also use expressions to perform logical or mathematical calculations on tag
values, and then monitor the expression value rather than the original tag value. For
example, you could use an expression to monitor whether a tag value has increased or
decreased beyond a threshold value: If Tag1 > 90 then 1 else 2.
For information about creating expressions, see Chapter 23.
Identify alarm conditions
Once you have identified the processes you want to monitor for alarms, and the tags or
expressions that will store the values representing the status of the processes, you must
determine the acceptable range of values for each tag or expression. Then you can set up
alarms to notify the operator when a value is outside the normal operating range.
Import and export alarm setup files
The Alarm Import Export Wizard in FactoryTalk View Studio allows you to export alarm
information to an XML file, and to import an alarm setup XML file.
For example, you can export an application’s alarm setup information, import the setup to
another FactoryTalk View application, and then modify it in the new application to suit
your requirements. Or, you can modify the file before importing it into the new
application.
You can use the Alarm Import Export Wizard to import alarm setup information that has
been created using an external programming tool or editor, or you can import a
FactoryTalk View XML file.
For more information about importing and exporting alarm setup files, see Appendix E.
How alarms work
This section provides an overview of the key components of your application’s alarm
system, and describes how the different parts work together.