Configuration of Item Properties

OPC-spezification allows to add additional information to single OPC-items (opc-item means : a TwinCAT variable). These optional functionality is named "OPC-Item-Properties" in the OPC-spec and allows an opc-client to browse and read these additional properties.

The configuration of these properties occurs in the PLC program by adding comments behind a symbol. These comments will be interepreted by the OPC-Server.

Sample:

lTemperatur : DWORD;
         (* ~
            (OPC : 1 : Make variable visible for
OPC-Server)
            (OPC_PROP[0005] : 3         :
OPC_PROP_RIGHTS, here Read AND Write Access)
            (OPC_PROP[0100] : Grad F     :
OPC_PROP_UNIT)
            (OPC_PROP[0101] : Demovariable     :
OPC_PROP_DESC)
            (OPC_PROP[0205] : We are the champions :
OPC_PROP_SND)
            (OPC_PROP[0206] : ..\..\info.html :
OPC_PROP_HTML)
            (OPC_PROP[0207] : ..\..\service.avi :
OPC_PROP_AVI)
         *) 

Each time compiling the PLC-project the PLC-Control will create the file <PLC-projectname>.tpy. This XML based file contains information about PLC-variables and their link to the OPC-server.
The OPC server will analyze this information of the TPY file., so configure the OPC-Server to know the file <PLC-projectname>.tpy.

The following table shows a list of all Item Properties: