7 OPC UA Types and Instances ToC Previous Next

7.13 WwEventCategoryEnumeration ToC Previous Next

This enumeration WwEventCategoryEnumeration represents the category of an event. The enumeration is defined in Table 29.

Table 29 – WwEventCategoryEnumeration Items

Name Value Description
ERROR 5    This category is used for error messages associated with problems that need human interaction.   An Error occurs if the situation has critical consequences for the machine process. For example, the protection of human life, of the environment, or of the machine itself, through safety mechanisms that block the process to prevent any harmful situation.This kind of situation cannot be solved automatically and confirmation by an operator is mandatory.
ALARM 4    The goal of an alarm is to inform operators about conditions in a timely manner and allow the operator to take some action before some consequences occur. The consequences may be economic (product is not usable and must be discarded), may be physical (overheating), may be related to safety (fire or destruction could occur) or any of a number of other possibilities. Typically, if no action is taken related to an alarm for some period of time the process will cross some threshold at which point consequences will start to occur, likely causing an Error condition.According to this definition an alarm message usually requires an acknowledgement and it may be decided that also a confirmation is needed.
WARNING 3    This category describes messages that in general could have moderate importance. Missing or ignoring such a message has no serious consequences.   The woodworking system could request acknowledgement or acknowledgement and confirmation if needed.(Warning message to operator, e.g. “tool life will soon be reached”)
INFORMATION 2    Messages of this category do not require a client to read them for normal operation.   The woodworking system can safely continue normal operation even if this message is ignored.(Help messages to operator, e.g. “select Auto mode and press Start”)
DIAGNOSTIC 1    This category is used for messages for debugging and diagnostic purposes.They can be ignored by clients (Diagnostic messages to operator, e.g. “system is ready”)
OTHER 0 No other event category applies or it is unknown.

This specification does not intend to determine in which manner acknowledgement and confirmation are given by operators: this could be done directly on a machine (e.g. through a SCADA or HMI) or/and by an OPC UA Client through OPC UA Alarms and Conditions mechanisms, if available.

Its representation in the AddressSpace is defined in Table 30.

Table 30 – WwEventCategoryEnumeration Definiton

Attribute Value        
BrowseName WwEventCategoryEnumeration        
IsAbstract False        
References Node Class BrowseName DataType TypeDefinition Other
Subtype of the Enumeration type defined in OPC 10000-5          
0:HasProperty Variable 0:EnumStrings 0:LocalizedText[] 0:PropertyType  

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