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SECTION
7.
MEASUREMENT PROGRAMMING EXAMPLES
The manual for the 101 Probe gives the
coefficients
of
the sth order polynomial used to
convert the
output in millivolts to temperature
(E
denotes
the power of
10
by which
the mantissa
is multiplied):
c0
-53.7842
c1
0.147974
c2
-2.18755E-4
c3
2.19046E-7
c4
-1
.1
1341E-10
c5
2.33651E-14
The 21X
willonly
allow
5
significant digits to
the
right
or left
o{
the decimal point
to be entered
from
the keyboard. The polynomialcannot
be
applied exactly as given
in
the 101 manual. The
initial millivolt reading must be scaled
if
the
coefficients
of
the higher order terms are to
be
entered with
the maximum number of significant
digits.
lf
0.001 is used as a multiplier on the
millivolt output, the coefficients are divided by
0.001 raised to the appropriate power (i.e.,
C0=C0,
C1
=C110.001,
C2=C2/.000001, etc.).
With
this adjustment, the coefficients entered
in
Parameters 4-9
of Instruction 55 become:
01:
P4
01:
5
02:
5
03:
1
04:.
1
05:
10
06:
2000
07:
1
08:
.001
09:
0
PROGRAM
Excite,
Delay,Volt(SE)
Reps
5000 mV
slow Range
lN Chan
Excite
all reps w/EXchan
1
Delay
(units.01sec)
mV Excitation
Loc
:
Mult
Offset
c0
-53.784
c1
147.97
c2
-218.76
c3
219.05
c4
-111.34
c5
23.365
FIGURE
7.15-1.
101
Thermistor Probes
Connected to
21X
02:
P55
Polynomial
01:
5
Reps
02:
1
X Loc
.03:
1
F(X)
Loc:
04:
-53.784
C0
05: 147.97
C1
06: -218.76
C2
07: 219.05
C3
08: -111.34
C4
09:
23.365
C5
7.16
MEASURING 107 TEMPERATURE
PROBE WITH 60 HZ REJECTION
The
107
temperature probe is normally
measured
with Instruction
11
which uses the
same measurement sequence
as lnstruction
5
with
a
fast integration voltage measurement.
The fast integration
does not reject 60 Hz noise.
In
environments where
60 Hz
is
a problem, the
107 probe
can be measured with Instruction
5
using the
slow integration time.
A multiplier of 800 in Instruction 5 is used to
scale the
voltage measurement for the
polynomial Instruction 55 which is used to
convert the
voltage measurement to
oC.
THERMISTOR PROBES
EX1
+
Hr I
21X
LO1
Ht2
RED
LEADS TO
SINGLE
ENDED
INPUT
CHANNELS
I-5
7-12
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