OPC AE
OPC AE
Supported Versions
1.0
1.10
Overview
OPC Alarms & Events (AE) is a specification developed by the OPC Foundation to standardize the way that alarm and event information is shared among systems. Using the standard, AE clients can receive alarms and event notices for equipment safety limits, system errors, and other abnormal situations.
Simple Events
Simple Events include the server events displayed in the Event Log (such as information, warning, error, and security events). The server supports the following filtering options for Simple Events for AE clients:
• Event Type Simple.
• Event Category Filter by server-defined categories. Each event is assigned to one category. Descriptions of the categories are as follows:
◦ Runtime Error Events Simple events that are shown as errors in the Event Log.
◦ Runtime Warning Events Simple events that are shown as warnings in the Event Log.
◦ Runtime Information Events Simple events that are shown as informational in the Event Log.
Condition Events
Condition Events are created by server conditions, which are currently only configurable through the use of the Alarms & Events plug-in. The server supports the following filtering options for Condition Events for AE clients:
1. Event Condition.
2. Category Filter by server-defined categories. Each event is assigned to one category. Descriptions of the categories are as follows:
◦ Level Alarms Events that are generated by process-level conditions. For example, tank level > 10.
◦ Deviation Alarms Events that are generated by deviation conditions. For example, tank level ± 10.
◦ Rate of Change Alarms Events that are generated by rate of change conditions.
3. Severity Filter by severity level. Levels range from 0 to 1000; 1000 is the most severe. Each event is assigned a severity.
4. Area Filter by a process area to get alarms and events from only that area. An area is used to organize alarm and event information.
5. Source Filter by source to get events from only that source. A source is an Alarms & Events area that was created by a source (such as a server tag) that belongs to an area.
Note: The Alarms & Events Plug-In allows conditions to be configured through server tags. For example, a Temperature tag can be configured through the Alarms & Events Plug-In to generate an event when the maximum value is reached. For more information on the Alarms & Events Plug-In, contact an OPC vendor.
Optional Interfaces
The AE server interface does not support the following optional interfaces:
• IOPCEventServer::QueryEventAttributes This interface manages event attributes, which are not supported by the server. Attributes allow custom information to be added to an event (such as special messages or server tag values). This also applies to the IOPCEventSubscriptionMgt::SelectReturnedAttributes interface and the IOPCEventSubscriptionMgt::GetReturnedAttributes interface.
• IOPCEventServer::TranslateToItemIDs This interface allows AE clients to get the OPC DA item related to the event. This is because in some cases, events are related to the value of a server tag.
• IOPCEventServer2: This interface allows clients to enable/disable areas and sources. This interface is not supported by the server, because it would allow one client to enable/disable an area or source for all clients.
Note: The AE server interface does not support tracking events.