Campbell Scientific CR510 Basic Datalogger - Manual (Page 108)

SECTION 9. INPUT/OUTPUT INSTRUCTIONS
9-4
PARAM. DATA
NUMBER TYPE DESCRIPTION
01: 2 Repetitions
02: 2 Range code (Table 9-1)
03: 2 Single-ended channel
number for first
measurement
04: 2 Excitation channel
number
05: 4 Delay in hundredths of
a second
06: 4 Excitation voltage
(millivolts)
07: 4 Input location number
for first measurement
08: FP Multiplier
09: FP Offset
Input locations altered: 1
*** 5 AC HALF BRIDGE ***
FUNCTION
This instruction is used to apply an excitation
voltage to a half bridge (Figure 13.5-1), make a
single-ended voltage measurement of the
bridge output, reverse the excitation voltage,
then repeat the measurement. The difference
between the two measurements is used to
calculate the resulting value which is the ratio of
the measurement to the excitation voltage. A 1
before the excitation channel number (1X)
causes the channel to be incremented with
each repetition.
The excitation "on time" for each polarity is
exactly the same to insure that ionic sensors do
not polarize with repetitive measurements. The
range should be selected to be a fast
measurement (range 11-15), limiting the
excitation on time to less than 800
microseconds at each polarity. A slow
integration time should not be used with ionic
sensors because of polarization error.
PARAM. DATA
NUMBER TYPE DESCRIPTION
01: 2 Repetitions
02: 2 Range Code (Table 9-1)
03: 2 Single-ended channel
number
04: 2 Excitation channel
number
05: 4 Excitation voltage
(millivolts)
06: 4 Input location number
for first measurement
07: FP Multiplier
08: FP Offset
Input locations altered: 1
*** 6 FULL BRIDGE WITH SINGLE ***
DIFFERENTIAL MEASUREMENT
FUNCTION
This Instruction is used to apply an excitation
voltage to a full bridge and make a differential
voltage measurement of the bridge output. The
measurement is made with the polarity of the
excitation voltage both positive and negative
(Figure 13.5-1). The result is 1000 times the
ratio of the measurement to the excitation
voltage. A 1 before the excitation channel
number (1X) causes the channel to be
incremented with each repetition.
PARAM. DATA
NUMBER TYPE DESCRIPTION
01: 2 Repetitions
02: 2 Range code (Table 9-1)
03: 2 Differential channel
number for first
measurement
04: 2 Excitation channel
number
05: 4 Excitation voltage
(millivolts)
06: 4 Input location number
for first measurement
07: FP Multiplier
08: FP Offset
Input locations altered: 1
*** 7 THREE WIRE HALF BRIDGE ***
FUNCTION
This Instruction is used to determine the ratio of
the sensor resistance to a known resistance
using a second voltage sensing wire from the
sensor to compensate for lead wire resistance.
The measurement sequence is to apply an
excitation voltage, make two voltage
measurements on two adjacent single-ended
channels, the first on the reference resistor and
the second on the voltage sensing wire from the
sensor (Figure 13.5-1), then reverse the
excitation voltage and repeat the measurements.
The two measurements are used to calculate the