SCXI-1300/1301 Terminal Block
8
www.ni.com
♦
SCXI-1102/B/C
If you are using a ground-referenced thermocouple, connect the
thermocouple positive and negative leads to CH+ and CH– respectively.
If you are using a non-referenced (floating) thermocouple, choose one of
the two options to ground the thermocouple:
•
Ground the negative lead of the thermocouple near the thermocouple
junction.
•
Ground the negative lead of the thermocouple inside the SCXI-1300
terminal block, by connecting CH– to CHSGND as shown in Figure 4.
In most applications, this is the most convenient grounding option.
Caution
Do not reference the thermocouple to ground at more than one point to avoid
measurement errors caused by ground loops.
Converting the Temperature Sensor Output Voltage to Temperature
The integrated-circuit temperature sensor outputs 10 mV/°C. If your
application software does not provide voltage-to-temperature conversion
for the cold-junction reference (CJR) of the SCXI-1300, you can determine
the CJR temperature using the following formulas:
where V
TEMPOUT
is the temperature sensor output voltage, and T(°F) and
T(°C) are the temperature readings in degrees Fahrenheit and degrees
Celsius, respectively.
Note
Average a large number of samples to obtain the most accurate reading.
Reading the Temperature Sensor in LabVIEW
In LabVIEW, the channel address string used to read V
TEMPOUT
depends on
which module is connected to the SCXI-1300. For more information about
channel-string arrays and the SCXI channel-addressing syntax, see the
LabVIEW Data Acquisition Basics Manual.
♦
SCXI-1100—use
ob
x
!
sc
y
!
md
z
!
mtemp
. This channel-address string
cannot be in a channel-string array with other channels on the same
SCXI-1100 module.
♦
SCXI-1102/B/C—use
ob
x
!
sc
y
!
md
z
!
mtemp
. This channel-address
string can be in the same channel-string array as other channels on the same
T
°
C
( )
100 V
TEMPOUT
(
)
=
T
°
F
( )
[T(
°
C
) ]
9
5
-----------------------
32
+
=
Summary of Contents for SCXI-1300
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