Page 814 - ExtendSim User Guide
P. 814

Data Management and Exchange
Technologies for communication
The easiest way to communicate using ADO is to use the Data Import Export block (Value library) shown here. Otherwise, use the ADO functions from the ADO_DBFunctions include file.
☞ When using ADO, make sure that the ExtendSim table and external database table have com- patible column formats and the same number of columns.
DDE (Windows only)
Dynamic Data Exchange (DDE) is a Windows operating system protocol through which appli- cations can exchange data. DDE allows applications to form DDE links from one application (DDE server) to another (DDE client) and obtain data in real time. As data changes at the server, the server sends the new data to the client for processing. Once the link is established, the applications exchange data without further user involvement.
Two applications linked by DDE are said to be engaged in a conversation. The server is the application that initiates the conversation; the client is the application that responds to the server. Unlike embedded objects, this conversation takes place between two windows.
DDE linking can be used for one-time data transfers and for continuous exchanges in which applications send updates to one another as new data becomes available. It is most appropriate for data exchanges that do not require ongoing user interaction. Some areas where it is useful are:
• Performing data queries, such as an ExtendSim model requesting information from an Excel worksheet.
• Linking to real-time data, such as scientific instruments, process control, or stock mar- ket updates
• Creating compound documents, such as an ExtendSim model that includes an Excel chart.
In ExtendSim, DDE technology is implemented through:
• Menu commands that establish a connection between two pieces of data. (See “DDE links (Windows only)” on page 744.)
• The Command block (Value library) for sending instructions to a spreadsheet, causing it to execute a macro. (See “Command” on page 782.)
• IPC functions that provide more flexibility than using just menu commands to create DDE links, such as the ability to set a value in Excel without establishing a link. (See the Developer Reference.)
Options in Data Import Export block
How To

   812   813   814   815   816