Instructions

UM-0085-B09 DT80 Range User Manual Page 78
RG
Multi Value Statistical Options
The statistical options described here are special in that they return multiple values. A channel can only have one return
value, so these options work by setting channel variables.
These channel options do not affect the usual reporting or logging of the channel’s readings.
Histogram (Hx:y:m..nCV)
The DT80 can be used to generate a histogram (frequency distribution) of channel samples by applying the histogram
channel option, which instructs the DT80 to
• divide the measured data range into a number of intervals called classes
• count the number of readings that occur in each class during the histogram period
• load each class count into a separate channel variable.
Then use another schedule to read, log and clear the channel variables.
Figure 19: Histogram
In addition, the DT80 automatically counts the number of under-range, over-range and total readings, and stores these in
three separate channel variables.
The format of the histogram channel option is:
Hx:y:m..nCV
where:
• x and y are the lowest and highest channel readings of interest, as shown in the above diagram
• m and n denote the range of channel variables (mCV to nCV inclusive) to use for storing count values
The channel variables are set as follows:
Channel Variable
Function
mCV
number of readings in the lowest class
...
(n-3)CV
number of readings in the highest class
(n-2)CV
number of readings under range (<x)
(n-1)CV
number of readings over range (>y)
nCV
total number of readings including those out of range
The range x..y will therefore be broken up into (n – m – 2) classes.
 Example — Histogram
To create a histogram of a temperature channel over five classes requires eight channel variables:
BEGIN"HISTO"
11..18CV=0
RA1S 1TT(H25.0:35.0:11..18CV)
RBX 16CV("Under") 11..15CV 17CV("Over") 18CV("Total")
RCX 11..18CV=0
END
The A schedule will report the temperature once a second. It will also accumulate a histogram with five temperature
classes and intervals of 2°C:
•
11CV counts readings in the first class (25.0 to 26.999°C interval)
•
12CV counts readings in the second class (27.0 to 28.999°C interval)
•
13CV counts readings in the third class (29.0 to 30.999°C interval)
•
14CV counts readings in the fourth class (31.0 to 32.999°C interval)
•
15CV counts readings in the fifth class (33.0 to 34.999°C interval)