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OPC-UA

OPC Unified Architecture (OPC UA) is an open-source protocol intended specifically for telemetry applications, i.e., sensor-to-cloud exchange. It supports a broad range of protocols and can function as a layer on top of TCP/IP stack, a websocket, or another connection type, depending on the implementation. OPC-UA is developed and supported by the OPC Foundation, which also maintains detailed documentation. Being the recognized standard under IEC 62541-5:2020, OPC-UA is partly supported by the Cloud.

Device Parameters

For device parameters not covered herein, see Device-Based Tags.

Address

Address of the target OPC-UA device, with transport layer specification. For example:

tcp://192.168.10.20:4840

Authentication Settings: Authorization strategy

Must be pre-configured on the target device; refer to the device manufacturer’s user manual for appropriate instructions.

Three options are available:

  • Anonymous
    No authentication. Not recommended for security reasons.
  • Username and password
    Authentication credentials as set up on the device.
  • Certificate
    Requires two .pem files: one for the certificate and one for the matching private key. Generate the files on the target device using its console-based or graphic UI, then drag-and-drop or select them in the browser’s file selector to be uploaded to the Cloud. Refer to the device manufacturer’s user manual for information on how to generate these files.

Tag Parameters

For tag parameters not covered herein, see Tag Editor.

Address

A string representing the NodeID assigned to the data endpoint to be associated with the tag; see OPC UA Node IDs for details. For example:

/8:Datalayer/8:datalayer/8:statistics/8:broker/8:backend-in

Writable

For more details, see Writable.

In contrast to Modbus or BACnet tags, this parameter is always unlocked in OPC-UA tag configuration. However, attempts to write a value from HMI Pages to a data endpoint that does not support writability will result in an error:

Tag values were not updated

External data type

For more details, see External data type.

Data type may not be configured Cloud-side for OPC-UA tags; therefore, the external data type selector must be used to specify if the data endpoint supplies/accepts scalar or array data. Data conversions apply.