Example. Pdf

String animation expression dialog calling out an I/O message tag.
6. 
Double-click the tag name in the 
Expression:
edit box to see how this tag is defined. If you
click on the 
Type
button to the right of the Tagname: you will see the first key piece of information
that is required to define the tag. In this case the tag is defined as an 
I/O Message
. Once a tag
is assigned a type (Discrete, Integer, Real, or Message), it will remain restricted to these foundation
types. The first time a tag is defined, you can select from all the tag types that are supported by
InTouch.

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10
InTouch Example Description
Figure 6
InTouch tag definition dialog.
7.
The second key piece of information that is needed to connect an I/O tag to the LNS DDE Server is
the 
Access Name
. InTouch uses Access Names to define the Application and Topic portions of
a DDE link. In this case we have defined the Access Name as 
LNS5LMNV
. Clikc the 
Access
Name…
button to show the following dialog box. These names were defined using the following
convention:
LNS#
. LNS is a shortened version of the application name, the # is
the handle for the Subsystem containing the targeted function block or device, and is
the topic type supported by the LNS DDE server.
Figure 7
InTouch Access name selection dialog.
8. 
Select 
LNS5LMNV
and click the 
Modify
button to review the definition of the Access Name. In
the 
Modify Access Name
dialog you define the Application and Topic portions of the DDE link.
The LNS DDE Server only supports DDE as a protocol. The default, 
‘Advise only active
items’
option is selected. This option allows you to limit the polling of the application to the
points currently monitored by active windows on screen and to points being logged or alarmed by
InTouch. InTouch is very efficient in the way it manages DDE links. Once a point is created,
InTouch does not destroy the link when the point is no longer in view. Instead, it deactivates the
point causing polling to stop while leaving the data structures in place so the next access to the

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InTouch Example Description
11
point will occur quickly. Not all DDE clients are created equal and may actually destroy the link
when a point is no longer in focus in the HMI application.
9. 
Back out of the series of dialogs just opened using the Cancel buttons to avoid any changes.
Figure 8