The ErrorConditions object contains a list of currently pending error messages.

The basis for the processing of error messages is the Alarm and Condition Model from OPC UA, which is defined in IEC 62541-9:2015.

An error message is represented by an object of the type AlarmConditionType or by a type derived from it.

The AlarmConditionType and its base types define various states such as EnabledState, AckedState or ActiveState and further properties such as Severity, Message, Time and SourceNode. The Retain Property indicates whether an error message is of interest to the client.

Changes to the status of an error message are supplied to the clients via Events. A client can request the current status for all error messages where Retain = true as an event via the ConditionRefresh method. Clients can thus request a list of pending error messages after establishment of a connection.

Clients can confirm error messages via Methods in order, for example, to change the AckedState of the error message.