Measurement Computing WavePort 312P rev.1.0 - Manual (Page 30)

3-14 Software Framework PowerVista/312 User’s Manual
⇒ Event/Demand Capture FIFO Overruns: should not be allowed. As noted above in Cycle-by-Cycle, a
moment in time will be missed for each FIFO overrun. This will cause demand logging to skip cycles and
event capture to miss events that could have occurred while the instrumentation was resetting.
Note: FIFO overruns occurring during Event/Demand Capture invalidate a portion of the collected data.
Demand logging should be mostly accurate, but will have missed several cycles within demand
intervals. Events captured during a FIFO overrun will exhibit a discontinuity across all captured
waveforms at the same moment. Events could also have been missed. If an event had a FIFO overrun
during its capture, it will have an additional label, "- FIFO", appended to its shot description.
3.10 Database View
The EasyPower Measure integrated database resides in the Database View at the bottom of the Acquisition
Window. The splitter bar allows more or less of the database to be viewed. As noted in Copy - Paste Shots, the
database has been designed for speed of writing data, and thus is time chronological with shots always being
appended to the end of the database. Shot numbers increment as they are appended.
There is virtually no limit (except Windows memory limitations) to the number of shots that a database can hold.
Event/Demand Capture however does have a 5000 event maximum limit for a given capture session. It is
recommended that database files be kept of reasonable length since the size of the files can become excessive.
Size of the file on disk is obviously determined by which type of shot was captured since each acquisition
feature saves a different amount of data. A table of disk memory allocations for each acquisition type within the
.dem file is supplied in Table 6.
Note: It is recommended that databases with less than 2000 events per database be created.
Table 6. Shot disk memory allocation for .dem file.
Shot Type kBytes
Phasor Diagram 15
Detailed Harmonics 109
Spectrum Analyzer 33
Cycle-by-Cycle (3600 cycles) 226
Event Capture (1 cycle) 4.5
Event Capture (225 cycles) 1,014
Demand Logging (3600 pts) 140
Demand Harmonics Logging (3600 pts) 120
3.10.1 Database Viewing and Selection
To view shots in the database the user may elect to:
• Scroll: using the scroll bar on the right of the Database View.
• Move and Display: using the up and down arrow keys (after at least one Display).
• Display: using a single left mouse click on any line.
The Database View list is a multiple selection list where (using standard Windows convention) the user can
select one, a series, or several intermittent shots for Shot Copy. The convention for performing these multiple
and single selections are:
• Single Left Mouse Click: selects, highlights and displays the shot clicked on.
• Single Left Mouse Click with Shift Key: selects and highlights a list of shots from the first single left
mouse click performed before this, to the shot clicked on, and displays the shot clicked on.
• Single Left Mouse Click with Ctrl Key: adds the shot clicked on to a list of other shots already
highlighted by any other method, and displays the shot clicked on.