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National Instruments Corporation
11
TBX-1328 Installation Guide
channels on the SCXI-1120/D, SCXI-1121, and SCXI-1126. You can read
a temperature at the beginning of the test and use that value with the data
that follows. Using this method assumes that there are no temperature
variations during the measurement period. If there are temperature
variations, the measurements can be less accurate. When using the
SCXI-1125 MTEMP can be scanned from any location in the scan list.
Notes
Do
not
place switch S1 in DTEMP mode. DTEMP mode is not supported.
When using SCXI-112
X
modules, the TBX-1328 does not provide open thermocouple
detection. To provide open thermocouple detection, you must provide a resistor to +5 V
and another resistor to GND, which defeats the isolation boundary and changes the
specifications.
Temperature Sensor Output and Accuracy
The TBX-1328 temperature sensor outputs 1.91 to 0.65 V from 0 to 50 °C.
LabVIEW, Measurement Studio, and NI-DAQ can convert a thermistor
voltage to the thermistor temperature for the circuit diagram shown in
Figure 5.
Note
The circuit diagram in Figure 5 is optional information you can use if you want
more details about the TBX-1328 temperature sensor.
Figure 5.
Temperature Sensor Circuit Diagram
4.7 k
Ω
1%
5 k
Ω
0.1%
1
2
1
2
2
+
R
T
(5 k
Ω
at 25
°
C)
10 µF
16 V
0.1 µF
0.1 µF
–t
°
+5 V
2.5 V
LM 4040
2.5 V
0.1%
V
TEMPOUT