8 OPC UA ObjectTypes

8.6 Notification

8.6.2 MessagesType

The MessagesType is used to define the object sending events. These events are used for errors, warnings and messages.

The MessagesType is formally defined in Table 54.

Table 54 – MessagesType Definition

Attribute	Value
BrowseName	MessagesType
IsAbstract	False
References	Node Class	BrowseName	DataType	TypeDefinition	Other
Subtype of the BaseObjectType defined in OPC 10000-5 i.e. inheriting the InstanceDeclarations of that Node.
0:GeneratesEvent	ObjectType	AlertType
0:GeneratesEvent	ObjectType	NotificationEventType

To differentiate between errors, warnings and messages on the interface, the following convention shall be used, with regard to the recommendations in OPC 10000-5:

Errors have a high Severity between 667 and 1000 and are using an AlertType.

Warnings have a medium Severity between 334 and 666 and are using an AlertType.

Messages have a low Severity lower or equal to 333 and are using a NotificationEventType.