CitectSCADA runtime behaves as a DDE server and automatically provides DDE access to the complete variable tag database with no further setup necessary.
To create DDE links to the CitectSCADA variable tags, use the DDE Client syntax. For syntax details, see DDE conversations and client syntax.
In the DDE Client call, the DDE Application name needs to be "Citect", the DDE Topic name needs to be "Variable", and the DDE Data item name needs to be the CitectSCADA tag name.
For instance, the PV1 tag value can be accessed from a cell in Excel containing the following formula:
If the CitectSCADA variable tag name contains spaces or non-alphanumeric characters, the DDE data item section of the DDE Client call syntax needs to be enclosed within single quotes. For example:
=Citect|Variable!'Process Variable 1'
CitectSCADA runtime and the DDE Client application (for example Excel) need to both be running on the same computer. For information about DDE conversations, see DDE conversations and client syntax.
To establish a DDE conversation between applications on the same computer, see Setting up DDE conversations.
To establish DDE conversations between applications running on different computers over the same network, see Network DDE.