Write Values to a DDE Application

To write a Plant SCADA variable value directly to an external DDE server application currently running on the same computer as Plant SCADA, use the Cicode DDEWrite() function.

For example, writing data from Plant SCADA to a Microsoft Office Application (using Plant SCADA as the DDE Client and the Office application as the DDE server), could be done using the following Cicode DDEWrite() function examples:

! Write PV1 to Excel
! Assumes the existence of Sheet1
DDEWrite("Excel", "Sheet1", "R1C1", PV1);

! Write PV1 to Word
! Assumes the existence of TestDDE.doc already loaded in Word
! containing the bookmark named TagPV1
DDEWrite("Word", "TestDDE", "TagPV1", PV1);
! MS Access does not support direct DDE writes.

This DDE function is one-way, so to update the tag value in the remote DDE server application, this function will need to be called every time the value of this Plant SCADA variable changes.

Writing directly to a DDE server assumes a prior knowledge of the DDE server. In the above example, the spreadsheet or document needs to exist and Excel or Word (as appropriate) needs to be running for the DDE communication to be successful.

Note:

• Instead of using the once only DDEWrite(), you could use the multiple use DDE handle function DDEhPoke().

• Verify that remote requests are enabled in the other application. For example, in Excel, you need to verify the Ignore other applications check box is cleared (the default setting).

• The High security setting (if selected) on Microsoft Office does not appear to affect the use of remote DDE Client requests with those Office applications. See Use DDE with Microsoft Office Applications.

See Also

Reading Values from a DDE Application