National Instruments BridgeVIEW - Manual (Page 30)

Chapter 1 Introduction
© National Instruments Corporation 1-7 BridgeVIEW User Manual
Events
An event is something that happens within the BridgeVIEW system.
Events can be divided into two groups: those that pertain to individual
tags and those that pertain to the overall BridgeVIEW system. Events
pertaining to tags include the following:
• A tag going in or out of alarm
• An operator changing the value of a tag
• An operator acknowledging an alarm
Events pertaining to the system include the following:
• The launching or shutting down of the Engine
• A new operator logging on
• An error from a server
The Engine also maintains alarm summary and event history information
pertaining to tags. This information can be viewed by the user’s HMI and/or
be logged to disk.
Historical Data Logging and Extraction
You can extract data from the historical database to view the trend of tag
data over time. The BridgeVIEW Engine manages logging data to the
Citadel Historical Database. A
trend is a view of data over time. Trends can
be real-time (current data) or historical (logged data). You can view logged
data with a user interface (HMI) or with the Historical Trend Viewer
(HTV). For more information about historical data logging and extraction
or the Citadel Historical Database, see Chapter 6,
Historical Data Logging
and Extraction , or Appendix B, Citadel and Open Database Connectivity .
Security
Environment security is built into BridgeVIEW and determines access to
certain parts of the BridgeVIEW environment. BridgeVIEW security is
broken into two general categories:
• BridgeVIEW Environment Access Privileges
• Operator Interface Security