OPC Client

This chapter explains the most important terms and presents the steps involved in starting a functioning OPC communication. The individual points will be dealt with in more detail in the subsequent chapters. However, this documentation cannot describe exactly how OPC works, and in particular the use of all parameters. It is necessary to study the relevant server documentation and/or the OPC Data Access specifications, in order to cover this subject area.


OPC (OLE for Process Control) is the utilization of OLE/COM technology for process-control systems. The specifications needed for this are laid down by the OPC Foundation (http://www.opcfoundation.org). The specification documents cover several areas:

  1. Data Access
  2. Historical Data Access
  3. Alarms and Events
Note: Historical Data Access is not used by this driver.
Chapter Description
OPC, basics General overview and links to the chapters
OPC under WinCC OA Possibilities of OPC client under WinCC OA
OPC server The OPC server is the program that collects the data from the hardware on one side, and makes it available to the OPC clients over the OPC interface on the other side.
OPC group The OPC group is a logical administrative unit for the OPC items in the server.
OPC item The OPC item contains the actual data; it is the representation of the data point in the OPC environment.
Reserved characters Restrictions for using characters
Initial setup of OPC communication Step by step to a working communication
Server installation and start-up Installation, Registration starting of the OPC server
Possible config entries
[opc] Config entries for OPC client
[opc_<server name>] Server specific config entries
Start OPC client Starting Manager WCCOAopc
DCOM Settings for Remote Servers Registration of a Remote Server
Communication Initializing connection, monitoring, termination via server /client..
Panel OPC address Configuration panel for the peripheral address of OPC client
Panel OPC server Configuration panel for OPC server data point
Panel OPC group Configuration panel for OPC group data point
Internal data points for OPC Used data points
_OPCServer Description of data point elements of the server data point
_OPCGroup Description of data point elements of the OPC group data point
OPC error messages Possible error messages
Glossary Abbreviations, terms and explanations
Quality Flags Description of the quality flags. These flags represent the quality state for a item's data value.