The Database Exchange control is developed in VB6 and is a single thread application. CitectSCADA as an ActiveX container will treat ActiveX controls as foreground objects. Thus a long running method of ActiveX control will hinder on the CitectSCADA main thread. For this reason, it is not recommended that an ActiveX control be running on CitectSCADA I/O Servers or critical CitectSCADA boxes, such as trend servers. For example, if you had a control on a CitectSCADA trend server that has a long running method, you might experience missing trend samples.
When you use Database Exchange control with CitectSCADA :
Currently the filter functionality of the Database Exchange control is not exposed as a public method or property. However, using a different SQL statement at runtime achieves the same result: take variable.dbf in the CitectSCADA Example project as an example. Assume the Database Exchange control occupies AN35.
SELECT * FROM Variable WHERE Name LIKE ‘%LOOP%’
Display all tags whose names start with “LOOP”.
SELECT * FROM Variable WHERE Name LIKE ‘%BIT%’
Display all tags whose names start with “BIT”.
FUNCTION UpdateRecordSource(STRING sAN,STRING sRecordSource)
In version 3.1.1 or later of Database Exchange control, the version number is displayed on the General tab on the properties form.