Oldham WX16, User Manual

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WX16 User Manual | 6
1.1 Data Display Screens
The WX16 Controller offers three distinct graphic displays for depicting the monitored
data. These are Bar Graphs, 24 Hour Trend and Combination. Each is shown in Figure
2.0.
1.1.1 Trend Screen
The WX16 Trend screen shown in Figure 2.0 displays a 24-hour trend of input data for
the channel selected. Horizontal tic marks are each hour and vertical tick marks are
each 10% of full scale. Dashed lines indicate alarm levels. The graphic LCD is 240
pixels wide, so each pixel represents 1/10 hour, or 6 minutes worth of data. The trend
is 100 pixels high, so each represents 1% of full scale in amplitude. Since each data
point must be collected for 6 minutes before it may be displayed, it is likely input values
will fluctuate during this interval. Therefore, MAX, MIN and AVERAGE values are
stored in RAM memory for each 6-minute subinterval. To accurately portray the trend,
a vertical line is drawn between MIN & MAX values for each 6-minute subinterval. The
AVERAGE value pixel is then left blank, leaving a gap in the vertical line. This is
demonstrated in the
noisy area of the 24-hour trend in Figure 2.0. If the MAX & MIN
values are within 2% of each other, there is no need for the vertical line, and only the
AVERAGE value pixel is darkened as in the
quiet areas.
The top portion of each trend screen indicates channel #, real time reading in
engineering units, measurement name, range, and MIN, MAX & AVERAGE values for
the preceding 24-hour period. The SI field on the top right indicates number of seconds
remaining in the current 6-minute subinterval.
1.1.2 Bar Graphs Screen
The WX16 Bar Graphs screen shown in Figure 2.0 allows all active channels to be
viewed simultaneously. Both engineering units values and bar graph values are
indicated in real time. Lines across the bars indicate the alarm trip points making it
easy to identify channels at or near alarm. A feature in the Systems menu tree allows
new alarms to always force the LCD to the bar graphs screen. This is useful for
applications requiring channels with alarms to be displayed.
1.1.3 Combination Screen
The WX16 Combination screen shown in Figure 2.0 offers a view of a single channel
but displays the data as a 30-minute trend, bar graph and large engineering units. It is
also useful for testing inputs for stability since MAX, MIN & AVERAGE values refresh
each time this screen is selected. For example, to test stability over a one-hour period
for an input, begin timing as soon as the channel is selected. One hour later, record the
MAX, MIN & AVERAGE values. The difference between MAX & MIN indicates peak to
peak excursions over the one-hour period and AVERAGE is the average for the hour.
Longer or shorter tests may also be run. The numeric value shown below the bar graph
indicates number of minutes samples have been taken. After 999 minutes the