Structure of the XML configuration files
Use this information to understand the structure of the XML configuration files delivered with the Probe for OPC Unified Architecture (UA).
The XML declaration
The XML configuration
files are XML documents that contain an XML declaration followed by
the <ListOfMonitoredItemCreateRequest> root element.
The document begins with the XML declaration. In this release of the probe, this declaration is:
<?xml version="1.0" encoding="UTF8" standalone="yes">The <ListOfMonitoredItemCreateRequest> root element
The root element holds the document's content and defines the default namespace. In this release of the probe, the syntax of the root element is:
<ListOfMonitoredItemCreateRequest
xmlns="http://opcfoundation.org/UA/2008/02/Types.xsd">
.
.
.
</ListOfMonitoredItemCreateRequest>Content of the root element
The root element
contains one or more <MonitoredItemCreateRequest> and </MonitoredItemCreateRequest> elements.
Each of these elements defines an item in the OPC UA server
that the probe wants monitored and what the probe wants to be notified
of for that item. You can set up the following types of notification
for any monitored item:
- Data change
- Event
Order of Elements
Unless otherwise specified the elements in the XML document appear in the order shown in this definition.
Case sensitivity
In XML documents, element and attribute names are case sensitive. Use the same case as specified in this definition. In addition, the content of some elements is also case sensitive. The description of individual elements includes information on case sensitivity, if any.
Content restrictions
There are restrictions on the content of some elements. For example, there may be a limit on the number of characters they can contain, or the content may be restricted to a defined set of values. The description of elements in this definition sets out any content restrictions.
Comments
You can include comments in the configuration files using the standard XML syntax. For example:
<!-- This is a comment -->Example configuration files
The probe provides two example XML configuration files:
- OpcUaEvent.xml: Contains definitions of subscriptions to events.
- OpcUaDataChange.xml: Contains definition of subscriptions of changes to data.
You can find both files in the $OMNIHOME/var directory.