Applies To:
  • CitectSCADA 2.01 3.00 4.10
Summary:
The DDEDRV driver allows Citect to connect to a DDEServer application and access the data managed by that DDE Server. Because different DDEServer applications may work slightly differently it is occasionally necessary to adapt the behaviour of the driver to suit the DDEServer. The driver supports some options to control its behaviour. 

Solution:
[DDEDRV]
unit name.AdvInitData = n
 
where unit name is the name of the IODevice as it appears in the Citect Project IODevice form
n is the initialisation mode for this unit and n can be:

0 No initialisation, all data items are displayed even if in they are not in an initialised state.
1 Initialisation by the driver actively making a DDE READ request.
2 Driver expects the DDEServer to notifiy the initial data items value. This is the default mode.

[DDEDRV]
unit name.PurgeTime = t

where unit name is the name of the IODevice as it appears in the Citect Project IODevice form
t is the time in seconds that an hot link will live if it is not being used. Links usually need to be purged so that a DDEServer knows when a data item is no longer required. The default purge time is 120 seconds.

See Also Q1848 for details on Hot and Cold links.

 
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