3-23
3.3.2.2 Reference Resistor Coefficients
These coefficients are factory set and similar to the temperature coefficients of section 3.3.2.1.
The reference resistor is approximately 10KΩ with coefficients chosen to provide a reference
value of approximately 0 °C. An AVG amount of approximately 50 is typical.
Any change made to either the reference resistor or the coefficients (with the exception of AVG)
requires that the temperature calibration of section 4.2.2 be performed on both temperature
probes.
3.3.2.3 Pressure Coefficients
The ZERO, SPAN, and LIN values are coefficients to the formula
Pressure = A + Bx + Cx
2
where A = zero coefficient
B = span coefficient
C = linearity coefficient
x = output of the A/D converter card.
These coefficients are automatically computed during pressure calibration (section 4.2.3)
AVG is the amount of averaging applied to the displayed value. Averaging is applied with the
formula
New Value = {(Previous Value *AVG) + New Reading}/(AVG + 1)
An AVG of zero (0) effectively eliminates averaging. An AVG that is very large has a
correspondingly large averaging affect. Non-integer averaging amounts are allowable; however,
negative amounts should never be used. An AVG of approximately 10 is typical, while an AVG
of 1000 would be excessively high.
The date indicated at the bottom of the screen is the last date of calibration or the date of the
most recent editing of any of the listed values. The date shown may not be edited and is updated
automatically during calibration or when changing coefficients on this screen.
LOW RANGE PRESSURE, Ps
Zero
[-.0609974
]
Span
[ 1.96204E-03]
Lin
[ 5.12663E-10]
Avg
[ 10
]
Last Cal Date 03/10/10
EDIT
NEXT
PREV
DONE
