Extension Object Support
- Last UpdatedFeb 05, 2025
- 2 minute read
The OPCUA driver supports OPC UA extension objects which contain a structure (or an array of structures) encoded in a binary format. Each structure member is represented as a separate tag in Plant SCADA.
The Plant SCADA tags are created during tag import. The OPC UA tag import component allows you to browse the supported extension objects and displays the Plant SCADA tags corresponding to the extension object elements.
It is only possible to browse and create tags for the simple OPC UA data types supported by the driver. The simple data type arrays inside the extension objects (BOOLEAN, INT32, and so on) are currently not supported.
When writing to a tag which corresponds to an extension object member, the driver has to update the entire extension object value as the OPC UA protocol does not allow to update the specific extension object element.
Before performing the write request, the driver reads the whole extension object value, updates the specified element and writes the extension object value to the server.
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LOSS OF CONTROL When configuring your system, you need to make sure the extension object value cannot be updated when it is being updated by the driver. Although the driver uses the most up-to-date extension object value when performing a write, if the extension object value is changed by the server at that time (for example by a PLC program), there is a chance the extension object value will be incorrect after the write. Failure to follow these instructions can result in death, serious injury, or equipment damage. |
