Event Types, Categories, and Conditions

The Historian alarm and event collector captures all event types, categories, sub-categories, and conditions supplied to it by the OPC Alarm and Event Server. Consult your OPC server documentation for more detail as to which categories, sub-categories, and conditions it provides.

Event Types

Three basic types of events are supplied by an OPC alarm and event server: Condition, Simple, and Tracking. Each of these types has its own categories, sub-categories, and conditions. For example, a Condition event may have a Level category, which itself may have several conditions, such as LO LO, LO, HI, and HI HI.

Condition: Condition events record the transition of states in an alarm. For example, a condition event could be recorded for an alarm when the level changes from LO to HI HI.
Tracking: Tracking events are not associated with conditions, but rather track activity between the OPC Alarm and Events Server and an OPC client. For example, if an operator acknowledges an alarm, a tracking event would be recorded.
Simple: Simple events record everything not covered by Condition or Tracking events. For example, if a device were to fail, a simple event would be recorded.

Event Categories

Event categories are used to group similar event types and are configured on the OPC alarm and events server. For example, you might set up categories for "System Events", "Process Events", and "Batch Events". You might likewise set up categories for different areas of your process, such as "Premix", "Dry Mix" or "Bake". Categories can hold multiple event types, and a given source can generate events for multiple categories.

Note: Category names must be unique within the OPC alarm and event server.

Event Conditions

Conditions are named states of alarms and events within the OPC alarm and event server. Conditions could include LO LO, LO, HI, and HI HI, as well as SYSTEM_FAILURE, LIMIT EXCEEDED, NORMAL STATE, and others. Conditions may also contain sub-conditions, which help to further granularize. Consult your OPC Server's documentation for a complete listing of its conditions.