Using CitectSCADA > Exchanging Data with Other Applications > Using DDE (Dynamic Data Exchange)

Using DDE (Dynamic Data Exchange)

Microsoft Windows DDE allows the continuous and automatic exchange of data between different Windows applications on the same machine without the need for any user intervention. For example, your company's Production group might use a spreadsheet application to graphically represent plant-floor data (product output). This could be dynamically updated with the latest live data using DDE to read values directly from CitectSCADA.

Windows DDE uses the DDE protocol to send messages between applications that share data.

Dynamic Data Exchange occurs between a DDE client application (which requests the data or service) and a DDE server application (which provides the data or service). The DDE Client starts the exchange by establishing a conversation with the DDE server, and requesting data or services. The DDE server responds to these requests by providing the data or services to the DDE Client. The DDE Client terminates the conversation when it no longer needs the DDE server's data or services.

Note: As the DDE protocol is not designed for high-speed data transfer, the use of DDE is only appropriate when data communication speed is not critical.