Page 770 - ExtendSim User Guide
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Data Management and Exchange
User interfaces for data exchange
box is unchecked) only the links that were defined by block developers through ModL code. The DB selectors and the GA popup menu on the right of the dialog specify which database or global array structure will be searched for. (Leaving the DB name or GA name popup menus to the default choices seen above will find any linked database or global array.)
When the Find Links button is clicked, ExtendSim opens the dialog boxes of all the blocks with the specified types of links.
☞ If the model is large and you specify all types of links this command can open many block dia- logs. It is usually advisable to search for specific types of links, so as not to have more dialogs open than needed.
DDE links (Windows only)
One method of sharing data between ExtendSim and another application is by creating a DDE link between the two applications. ExtendSim supports two types of DDE links:
1) Asaclientapplication,importingdataintoExtendSimbylinkinganexternalapplication’s file to an ExtendSim model.
2) Asaserverapplication,exportingdatafromanExtendSimmodeltoanexternalfile.
The external application and ExtendSim communicate with each other in a type of data conver- sation, with one application (the server) sending the data and the other application (the client) responding. A DDE link is a special registered Clipboard format that identifies the piece of data in the conversation. These are “hot” links, causing the server to simultaneously notify the client of the change and send the changed data to the client whenever the value of the specified data item has changed.
☞ This communication is unidirectional; data changes made in the server file affect the client file, but not vice versa.
The underlying technology that supports DDE linking is Dynamic Data Exchange (DDE), a Windows operating system protocol through which applications can exchange data. It is described fully at “DDE (Windows only)” on page 788. Microsoft Excel is an example of an external application that support DDE links.
☞ For data to be exchanged, DDE linking requires that the windows of both the server and the cli- ent files be open.
Creating a DDE link
DDE links from external applications are created and managed using DDE Link commands in ExtendSim’s Edit menu. Use those commands to link a value or values from the external appli- cation to parameters and data table cells in ExtendSim.
• To create an outgoing link from ExtendSim, use the Edit > Copy command in ExtendSim and the external application’s linking commands, such as Paste Special.
• TocreateanincominglinktoExtendSim,usetheEdit>PasteDDELinkcommand.This command will only be active if all of the following is true:
• TheexternalapplicationsupportsDDElinks.
• Both the external file and the ExtendSim model have been named and saved.
• Both the external file and the ExtendSim model are open.
• TheClipboardcontainsdatathathasbeencopiedfromtheexternalapplication.
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