National Instruments NI USB-TC01 Bedienungsanleitung Seite 7

NI USB-TC01 Circuitry
© National Instruments Corporation
If you are unsure which of the thermocouple leads is positive and which is
negative, check the thermocouple documentation or the thermocouple wire
spool.
Thermocouple
Figure 5. Connecting a Thermocouple Input Signal to the NI USB-TC01
For best results, NI recommends the use of insulated or ungrounded
thermocouples when possible. If you need to increase the length of your
thermocouple, use the same type of thermocouple wires to minimize the
error introduced by thermal EMFs.
Temperature measurement errors depend in part on the thermocouple type,
the temperature being measured, the accuracy of the thermocouple, and the
cold-junction temperature. Error graphs for each thermocouple type
connected to the NI USB-TC01 are shown in the
The NI USB-TC01 device's thermocouple channel passes through a
differential filter and is sampled by a 20-bit analog-to-digital converter
(ADC), as shown in Figure 6.
TC+
TC
TC−
Figure 6. NI USB-TC01 Input Circuitry
TC+
TC–
3.3 V
10 MΩ
Low pass filter
and
protection
10 MΩ
Isolated
GND
7 NI USB-TC01 User Guide and Specifications
USB-TC01
Specifications section.
Isolated
ADC