Rockwell Automation FactoryTalk View Site Edition Users Guide - Manual (Page 633)

24 • A DDING LOGIC AND CONTROL
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Using multiple derived tag components
You can create multiple derived tag components, for example, to group derived tags that
need to be evaluated at different rates.
Each HMI server in an network distributed application can run up to 20 derived tag
components, with up to 1,000 tags in each component.
Modifying existing derived tag components
You can modify derived tags during development, or when you run the application.
If you change an derived tags component at run time, the changes will not take effect until
you stop and then restart derived tags processing. For information about starting and
stopping derived tags, see page 24-5.
Starting and stopping derived tags processing
There are many ways to start and stop derived tags processing. Choose the way that works
best for the application.
To provide an operator with a way start and stop derived tags processing, use FactoryTalk
View commands and macros in conjunction with graphic objects. For details about
FactoryTalk View command syntax, see the FactoryTalk View Site Edition Help.
In the following methods, <component> represents the name of a derived tags file.
Starting derived tags in network and local station applications
For network applications, it is best to start derived tags processing using a server
component such as a startup macro, or using event processing.
Using clients to start and stop derived tags is not recommended, because one client might
stop a derived tags component that another client is using.
Use one of the following methods for network applications:
 In HMI Server Properties dialog box, click the Components tab, select the check
box, Derived tags, and then select a derived tag component.
The derived tag component will start the next time the HMI server runs, or when the
HMI server’s components are started manually.
 In the Macros editor, create a macro that contains the command, DerivedOn
<component>. In the HMI Server Properties dialog box, click the Components tab,
select the Macro check box, and then specify the macro. Derived tags processing will
start when the HMI server runs.
 In the Events editor, specify the DerivedOn <component> command as the action for
an event.