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

DDE function types

There are two classes of DDE functions in Cicode, the original DDE functions and the later DDEh functions.

DDE functions

The original Cicode DDE functions do not return a DDE Channel Number and were designed to insulate the user from the need to manage DDE Channels. The DDERead(), DDEPost(), DDEWrite(), and DDEExec() functions each perform a single exchange of data. Each of these functions starts a DDE conversation with the external application, sends or receives the data (or command), and ends the conversation - in one operation.

DDEh functions

The Cicode DDEhfunctions were introduced to afford more control over DDE communications, especially for Network DDE and for circumstances where it is necessary to explicitly terminate and re-initiate a DDE Channel (after deleting rows from a table for example).

The DDE handle (DDEh...)functions return a handle to the conversation - a DDE channel number.

Use the DDEh handle functions for Network DDE, and for Access DDE.

See Also