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Mapping Tags to OPC UA Variables

Last Modified: November 7, 2019

Interpret variables from an OPC server as SystemLink tags to track, update, or visualize external data within your system.

Variables are the OPC equivalent of SystemLink tags. Before you can read or write OPC UA variables as SystemLink tags, you must install NI SystemLink Server OPC Module, connect to an OPC server, and ensure SystemLink supports the data type of the variable.
  1. In the root directory on your OPC session, navigate to the location of the variable on the OPC server.
  2. Click Create monitor to connect the variable to a tag. Refer to the following table to determine which SystemLink data type corresponds to the data type of your OPC UA variable.
    OPC UA variable data type SystemLink tag data type
    • bool
    • boolean
    Boolean
    • float
    • double
    Double
    • int
    • int32
    • byte
    • short
    • int16
    • uint16
    • uint
    • number
    Int
    • uint32
    • uint64
    UInt64
    • bytestring
    • string
    String
    • datetime
    • utctime
    DateTime
    A monitor watches the OPC UA variable and writes its values to a corresponding SystemLink tag. Data from the OPC UA variable will now show as tag data in Tag Viewer, and you can visualize this tag data with Dashboards.
  3. Optional: To temporarily stop the monitor from writing to a tag, click Pause Monitor. To remove the connection between SystemLink and the OPC UA variable, click Delete Monitor.

After you map a variable to a tag, you can read values of the tag as it updates. The OPC UA variable will also update with any changes you make to the corresponding SystemLink tag.


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