Campbell Scientific CR10X Measurement and Control System - Manual (Page 138)

SECTION 9. INPUT/OUTPUT INSTRUCTIONS
9-6
05: 4 Delay (0.01s)
06: 4 Excitation voltage
(millivolts)
07: 4 Input location number
for first measurement
08: FP Multiplier
09: FP Offset
Input locations altered: 1 per repetition
*** 9 FULL BRIDGE WITH EXCITATION ***
COMPENSATION
FUNCTION
This instruction is used to apply an excitation
voltage and make two differential voltage
measurements. The measurements are made
with both positive and negative excitation
voltage. The measurements are made on
sequential channels. The result is the voltage
measured on the second channel (V
2
) divided
by the voltage measured on the first (V
1
). If V
1
is measured on the 2.5 V range (code 5,15, 25
or 35 in Parameter 2), then the result is 1000
times V
2
/V
1
. A 1 before the excitation channel
number (1X) causes the channel to be
incremented with each repetition.
When used as a 6 wire full bridge (Figure 13.5-
1), the connections are made so that V
1
is the
measurement of the voltage drop across the full
bridge, and V
2
is the measurement of the bridge
output. Because the excitation voltage for a full
bridge measurement is usually in the 2.5 V
range, the output is usually 1000 V
2
/V
1
or
millivolts output per volt excitation.
When used to measure a 4 wire half bridge, the
connections are made so that V
1
is the voltage
drop across the fixed resistor (R
f
), and V
2
is the
drop across the sensor (R
s
). As long as V
1
is
not measured on the 2.5V range, the result is
V
2
/V
1
which equals R
s
/R
f
.
PARAM. DATA
NUMBER TYPE DESCRIPTION
01: 2 Repetitions
02: 2 Range code for V
1
(Table 9-1)
03: 2 Range code for V
2
(Table 9-1)
04: 2 Differential channel
number for first
measurement
05: 2 Excitation channel number
06: 4 Excitation voltage
(millivolts)
07: 4 Input location number
for first measurement
08: FP Multiplier
09: FP Offset
Input locations altered: 1 per repetition
*** 10 BATTERY VOLTAGE ***
FUNCTION
This instruction reads the battery voltage and
writes it to an input location. The units for
battery voltage are volts. At approximately 9.6
V the CR10X suspends measurements.
PARAM. DATA
NUMBER TYPE DESCRIPTION
01: 4 Input location number
Input locations altered: 1
*** 11 107 THERMISTOR PROBE ***
FUNCTION
This Instruction applies a 2 VAC excitation
voltage to Campbell Scientific's Model 107
Thermistor Probe, makes a single-ended
voltage measurement across a resistor in series
with the thermistor, and calculates the
temperature in °C with a polynomial. A
multiplier of 1 and an offset of zero yields
temperature in degrees Celsius. The maximum
polynomial error from -40°C to +56°C is given
here:
Curve Fit Error --
Range (°C) Error (°C)
-40 to +56 <
±1.0
-24 to +48 < ±0.1
TABLE 9-3. Excitation/Integration Codes
Code Result
0x excite all rep with channel x
1x increment chan x with each rep
2x excite all reps with channel x, 60 Hz
rejection, 10 ms delay
3x excite all reps with channel x, 50 Hz
rejection, 10 ms delay
4x increment chan x with each rep, 60 Hz
rejection, 10 ms delay
5x increment chan x with each rep, 50 Hz
rejection, 10 ms delay