COM in WinCC OA, basics

COM stands for Component Object Model, a specification for developing modular software components which can be used by each COM compatible application. COM components can be easily integrated in such applications and can even be removed from an application at run time. COM components can be programmed in various different programming languages although C++ is used mostly. The specifications OLE, ActiveX and DirectX are based on the COM technology.

Via COM the objects of applications are open for development programs, macro languages and other applications that support automation. Via a spread sheet program , for example, a table, a chart, a cell or a cell space may be open whereas all objects have a different object type. A word processor may open its objects like an application, a document, a paragraph, a bookmark or a choice.

If an application supports COM you can access the open objects and change them by calling methods for this object or by calling the properties of the object and by defining them.

When changing data via COM a COM component takes care of the data exchange on the Excel side (currently only Excel is supported), on the WinCC OA side the own manager.

The ComManager contains four COM objects, which are responsible for different tasks. The ComManager object encapsulates a complete WinCC OA manager and provides access to the data points of WinCC OA whereas the functions are similar to the CTRL functions.

The ReportExt object is an extension of the ComManager object implemented especially for the Excel report. The Excel report and the ReportExt object are not described in detail here.

The ProjAdmin and ProjAdminAuto objects can be used to access information of installed WinCC OA projects. The ProjAdminAuto object can also be used in script languages like vbScript.