Campbell Scientific CR510 Basic Datalogger - Manual (Page 93)

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
7-15
The multiplier, m, is calculated to convert the
reading to feet of water.
m = 0.0151 (psi/digit)
∗
2.3067 (ft of water/psi)
∗
-1000 digits/kHz
2
= -34.831 ft of water/kHz
2
After the probe reaches thermal equilibrium, the
initial temperature, t
0
, is measured to be 24
°
C.
The water column above the sensor is referred
to as the "Reading". The Reading decreases
with increasing "Distance" from lip of well to
water surface so the Distance is computed by
subtracting the Reading from the Offset as
shown in Figure 7.13-2.
The "Initial Distance" to the water surface is
measured with a chalked line to be 47.23 feet
below the lip. The first time the program is
executed, the program calculates the offset
(Offset = Distance + Reading) required to obtain
a reading of 47.23 feet. The offset is stored in
Location 4 and applied to subsequent
measurements.
NOTE: Following program compilation in
the
∗
0 Mode, all input locations are set to
zero. This fact is utilized to detect the first
execution following a program compilation.
The example assumes the sensor has been
connected as shown here.
CR510 & AVW1
FIGURE 7.13-2. Well Monitoring Example