Opc Foundation - Siemens SIMATIC PCS 7 Function Manual

COMobjects can be understood as extensions of the operating system. They are not
dependent on programming languages and are available in principle to all applications.
The data and code of the object are not directly accessible to the user of the COMobject.
DCOM
DCOM is the acronym for "Distributed Component Object Model". It is based on COM
technology and provides the additional option of communicating over a network.
Object
Objects are defined by properties and methods that can be used on objects.
Events
An event is used to control program flow. Program execution is not linear, instead special event
handling routines are executed whenever a specific event occurs.
In terms of OpenPCS 7 and the OPC standard, Events mean messages / operation messages
of the PCS 7-system.
DLL
It is possible to use DLLs with Microsoft Visual Basic (VB) and Microsoft Visual Basic for
Applications (VBA). DLL stands for Dynamic Link Library. A DLL is a dynamic link library. Users
can link the functionalities of a DLL into their own applications. If you want to program an
OPCclient with VB, make sure that the relevant automation interface DLL is selected in the
VB Editor in "Project > References".
Collection
Collections are objects that support count and item properties. A collection consists of a certain
number of items. An item can be collection-specific, any data structure, or an object. The count
property specifies the number of items in a collection. In Microsoft Visual Basic, each item in
a collection can be identified using loops.
2.3

OPC Foundation

OPC Foundation
The aim of the OPC Foundation is to ensure compatibility between different subsystems in
automation and process control engineering. Compatibility is achieved by creating and
maintaining open specifications for the standardization of communication between subsystems
of different manufacturers. This allows process data, alarms and messages as well as archived
process data to be exchanged between subsystems regardless of their manufacturer.
OpenPCS 7
Function Manual, 05/2012, A5E02780178-02
Basics
2.3 OPC Foundation
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