Micromod Micro-PWC: 53PW6000 MicroPWC Configuration Guide - Manual (Page 273)

Micro-PWC CONFIGURATION GUIDE
Trends 253
7.3.3 Trend Parameters: Segment Size
The horizontal axis of the trend is divided into 5 segments; the end of each segment is marked by a long
tick mark and a time and date stamp. Two parameters determine the size of a segment: Seconds and
Points.
The Seconds parameter is used to assign the number of seconds in a segment. By default, this parameter
is set to 60 seconds.
The Points parameter determines the maximum number of trend points which can be plotted in a segment.
By default, a maximum of 60 points can be plotted per segment. The number of points determines the
resolution of the trace. Do not assign more than 600 points to a segment.
To obtain a normal (non-compressed) display, the number of Points assigned per segment should not
exceed the number of Seconds per segment.
To position points on the trend graph, the Micro-PWC uses an internal algorithm that divides the number of
seconds in the segment by the number of points in the segment, yielding the number of time intervals in
the segment:
number of seconds / number of points
The default settings of 60 points and 60 seconds per segment thus yield the equivalent of a 1:1 compres-
sion ratio. It is possible to imitate the effects of data compression by varying these settings. For example,
setting Seconds to 120, with Points set to 60, creates a trend trace which appears to have a compression
ratio of 2:1.
The Micro-PWC locates the points which lie within each time interval. If one point is found, the value of the
point is used to plot it on the trend display. If more than one point exists within the interval, the assigned
Display Option (MINimum, MAXimum, AVeraGe or INSTantaneous) is used to calculate one value from all
points which exist in the interval. This value is then plotted on the trend display. (If the INSTantaneous dis-
play option is used, the last value found will be used to plot the point on the trend display.) The resulting
value is used to plot the point on the trend display. If no points are found in an interval, no point is plotted
for that interval.
This method of plotting trends permits greater flexibility in trend configuration. For example, points with dif-
ferent collection rates can be plotted on the same trend graph, and non-periodic data can also be trended.
7.3.4 Trace Configuration
Up to 8 traces can be configured on each Trend display. Each trace appears in a different color; the color
for each trace is indicated on the colored button which appears to the left of the tagname, above the trend
graph.
To configure a trend trace, click the desired Trace Number button on the Trend Configuration window. A
window entitled Trend Trace Configuration will appear. Trend trace parameters which can be configured via
this window include:
• Historical Tagname
• High and Low limits for the trace
• Default Trace State (On or Off)
• Display Options (Min, Max, Avg, Inst)
• Description
✎ Note The tick marks which divide the segments on the time axis (x axis)
of the trend graph are for visual reference only, and do not
necessarily reflect the actual number of time intervals used by this
algorithm.