The trend system described here operates under the TSENTRY real time control system. It is a data collection system that supports the following functions:
Acquisition of process data from global common areas and from messages received from remote systems
Acquisition of data at precise user-defined intervals
Maintenance and storage of process data for some user-defined length of time
Buffering of trended process data to memory areas and disk files
Serving data requests from trend clients
Support of both static trends (variables trended continuously during system operation) and dynamic trends (variables trended on demand at the request of remote clients)
Display of trend data on web based screens
Monitor trend data for events and record data to individual disk-based data files for later review
Play back previously recorded trend data from historical trend files.