CoDeSys OPC-Server

The CoDeSys OPC-Server is part of the standard delivery package of CoDeSys and
is based on the 3S-Smart Software Solutions PLCHandler.
It can be operated under Windows XP and supports the following OPC specifications:

General overview OPC-Server{fettende}

OPC1 is a standardised interface giving access to process data. It is based on the Microsoft standard COM/DCOM2 and was extended to meet the needs of data access in the automation process where it is mostly used to read and write data from the controller. The typical OPC clients are visualisations and programs for recording operational data etc. PLC systems and field bus cards are usually supplied with an OPC server.
The OPC server is not a passive subprogram but an executable program which is started as soon as a connection is established between the client and the controller. It can therefore inform the client whenever the value of a variable or its status has changed.

The OPC Server offers all variables (called items in OPC) which are available in the controller (item pool or address). These so called items are managed in a data cache which allows for fast access to the item values. Direct, non-cached access to the items of the controller is also possible. OPC-Serverc data can be grouped. When doing so we differentiate between public groups which are provided by the OPC server and private groups which the client sets up himself.

Overview CoDeSys V3 OPC-Server

Communication between the CoDeSys OPC-Server 3 and a CoDeSys V3 controller is effected via the CoDeSys Gateway-Server V3. Other than the Gateway-Server V2.3 the V3 Gateway-Server is not bound to the Windows operating system and can be located anywhere within the controller network (this does not apply to embedded controllers).

The picture below shows the possible structure of a CoDeSys V3 controller network:

:

In order to be able to use the CoDeSys V3 OPC-Server it is necessary to add an object "Symbol Configuration" to the object tree beneath the application.


In the object "Symbol Configuration" the user chooses the variables which are to be made available to the OPC-Server.


Finally, an implicitly created CoDeSys application which provides the data is loaded onto the controller. This means that an OPC-Client which is connected to the OPC-Server can browse and make use of this data (usage is of course dependant on set access rights).