DirectOPC Interface

All client components that use OPC Systems.NET Tags as a data source can also use values directly from OPC Servers with the DirectOPC interface.  Using this method you will not have to create an OPC Systems.NET Tag if you just want to read or write an OPC Item in your .NET or web application.  DirectOPC items are also supported in trending and data logging.

The following example uses an OPC Systems.NET Tag to demonstrate using DirectOPC, but most likely you will be defined DirectOPC items in the client applications like your HMI, trending, data logging, recipes, .NET application, and Microsoft Excel Workbook.

 

Step

Task

1

Using Configure-Tags create a new Tag with the name CalcDirectOPC.

Select the local Service or remote Service that has the OPC Server you want to connect to.

2

Select the new CalcDirectOPC Tag and set the Data Source as Calculation.

 

3

Use the Edit Calculation button at the right to show the Calculation editor.

Select the Insert Tag button and select the plus icon to the left of DirectOPC.

A list of OPC Servers installed on the system you are currently connected to.

 

 

Browse one of your OPC Servers for an OPC Item and set the OPC Update Rate and desired Data Type.

The Tag name is returned with the following portions.

[DirectOPC:KEPware.KEPServerEx.V4\Channel_1.Device_1.Tag_1:DirectOPCUpdateRate:1:DirectOPCDataType:Double Float:DirectOPCAccessPath:]

 

OPC Server: KEPware.KEPServerEx.V4

OPC Item: Channel_1.Device_1.Tag_1

OPC Update Rate: 1

Data Type: Double Float

All client components can use this alternative syntax for connecting directly to OPC Servers.  This provides a direct pass through for OPC Items on local and remote systems.