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PATA
[YPE
I
l2
2
2
2
01:
02:
03:
04:
4
'4
4
iFP
FP
05:
06:
07:
08:
09:
PARAM.
NUMBER
DESCRIPTION
Repetitions
Range code
Input
channel number for
first measurement
Excitation channel
number
Delay (0.01s)
Excitation voltage
(millivolts)
Input location number
for
first measurement
Multiplier
Offset
Input
locatiQns
altered:
1
per measurement
***
9
FULL BRIDGE WITH EXCITATION
***
COMPENSATION
FUNCTION
This instrucfion is used to apply an excitation
voltage and make
two differential voltage
meas
then reverse the polarity
of
the
excitation afrd repeat
the measurements. The
measu
are made on sequential
result
is
the
voltage measured
on
the exci
channel
SECTION
9.
INPUT/OUTPUT INSTRUCTIONS
PARAM.
DATA
NUMBER
TYPE
DESCRIPTION
Repetitions
Range code
for
Vl
Range code for V2
Input
channel number for
first measurement
Excitation channel
number
Excitation voltage
(millivolts)
Input location number
for
first measurement
Multiplier
Offset
lnput locations
altered:
1
per measurement
*** 10
BATTERY
VOLTAGE
***
FUNCTION
This instruction reads the battery voltage and
writes
it
to an input location. Battery voltage
is
stored
in
volts.
PARAM.
DATA
NUMBER
TYPE
DESCRIPTION
01:
4
Input location
Input locations
altered:
1
*** 11
107
THERMISTOR
PROBE
***
FUNCTION
This instruction applies
a
4 VAC excitation
voltage
to Campbell Scientific's Model
107
Thermistor Probe, makes
a
fast, single-ended
voltage measurement on the 15mV range and
then calculates
the temperature in degrees C
with
a polynomial. The maximum polynomial
error
from
-40oC
to +55oC is given below:
Curve Fit Error
--
Range
(oC)
2
2
2
2
2
4
4
FP
FP
01:
02:
03:
o4:
05:
06:
07:
08:
09:
channels.
the second
the second phannel
(Vr) divided
by
the voltage
measured
Qn
the
first
(V1).
lf
V1
is measured on
(code 5
or 15 in Parameter
2),
then
the
is 1000
timesV2A/1.
Al
before
number (1X) causes
the
channelto
be incremented
with each repetition.
When used as
a 6
wire full bridge (Figure 13.5-
1),
the conrtections
are made so that
V.t
is
the
measuremQnt
of
the voltage drop across the full
bridge, and V2
is
the measurement of the bridge
output.
Bedause
the excitation voltage for
a
full
bridge meaburement is usually
in
the 5V range,
the
output
i$
usually 1000
V2A/1
or millivolts
output per volt excitation.
When used to measure a
4
wire half bridge, the
connectionq
are made so that
V1 is
the voltage
drop acrosg the
fixed resistor
(R),
and
Vr
is
the
drop acrosg the
sensor
(R.).
As long as
V1
is
not measurpd
on
the 5V range, the result
is
VrA/1 whic$
equals
Rs/Rf.
The
fast integration time used in Instruction
11
does not provide rejection of 60 Hz
noise.
See
example 7.16
for a method of measuring the
107
thermistor
where 60 Hz noise is a problem.
-40
to +55
-35
to +48
Error
(oC)
+1.0
+0.1
9-5
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