21
5
ADVANCED CONFIGURATION LEVEL…
•
Maths
5.1.4
Maximum and Minimum Value – Fig. 5.1
If the High Value function is selected the maths result holds the
maximum
value measured on an input variable. If the Low Value
function is selected the maths result holds the
minimum
value measured on an input variable. The maths result can be reset to its
current value by an internal or external digital signal.
Fig. 5.1 shows the process variable from a flow meter which is continually varying with time. The maximum and minimum values
are the highest and the lowest samples taken since an external reset last occurred. The external reset can be independent of the
average reset signal.
5.1.5
Real Time Average
The real time average function averages a continually varying input over a set time scale, between 1 and 1440 minutes
(24 hours). Any process variable, remote set point or other maths block result can be averaged. The maths result can be reset to
its current value by an internal or external signal.
Fig. 5.1 shows the process variable from a flow meter which is continually varying with time. At 0 minutes an external digital input
signal resets the average to the current value measured. The process variable is then sampled for 10 minutes. The average
function result is the average value of the process variable over the 10 minutes sampled.
Fig. 5.1 Example of Average, Maximum and Minimum Functions
Average Time (10 Minutes)
Minimum Value
PV
(Flow Rate)
Time (Minutes)
0
10
Maximum Value
External Reset Signal
Average
Summary of Contents for COMMANDER 1900 Series
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