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The DARS Archiver uses a set of fixed size files containing a circular set of fixed length records to record plant data at periodic intervals. The collection method may vary by point among any of these four methods:
- Last Value
- The last known value is recorded, regardless of any changes made since the previous sample.
- Average
- The average of all values (last value taken once per second) across the sample interval
- MaxVal
- The largest value recorded during the sample interval
- MinVal
- The smallest value recorded during the sample interval
The archiver may be recording to as many as eight different files (each of a different time sampling rate) concurrently. The file names, location, sample rate and record counts are specified in the DARS.INI file, located in the PICS\Config folder.
The most common use for the data recorded by DARS is to perform historical backfill for strip charts.
The DARS Server provides access to the archive files for the DARS Retrieval program (and other clients) using a TCP/IP interface. By using a network interface, it doesn't matter if the retrieval program runs on the same or a different machine, as long as a network connection is possible.
The DARS Retrieval interface provides a mechanism for end-users to request historical data from DARS and have it written to a file on their system in any of a number of formats. A current directory of the data stored in the archive files is displayed in the upper right, allowing the user to determine the best resolution available for data to be retrieved. The Refresh button will update the directory on demand.
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