Contents
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National Instruments Corporation
Using Programmable Ground-Referencing .................................................................. 3-4
Using Programmable Open-Thermocouple Detection ................................................. 3-5
Measuring Temperature with Thermocouples.............................................................. 3-6
Auto-Zero ........................................................................................ 3-9
Programmable Ground-Referencing................................................ 3-9
Programmable Open-Thermocouple Detection............................... 3-10
AC Noise Effects ............................................................................. 3-10
Thermal EMF .................................................................................. 3-10
Connecting Your DC Voltage Signal............................................................. 3-11
Input Ranges .................................................................................................. 3-11
Optimizing Measurements ............................................................................. 3-12
Auto-Zero ........................................................................................ 3-12
Programmable Ground-Referencing................................................ 3-12
Programmable Open-Thermocouple Detection............................... 3-13
Source Impedance............................................................................ 3-13
AC Noise Effects ............................................................................. 3-13
Thermal EMF .................................................................................. 3-13
Measuring Temperature with RTDs and Thermistors and Measuring Resistance....... 3-14
Relationship of Resistance and Temperature in RTDs.................... 3-14
Connecting Your RTD ................................................................................... 3-16
Introduction to Thermistors ........................................................................... 3-18
Resistance-Temperature Characteristic of Thermistors................... 3-20
Connecting Your Thermistor ......................................................................... 3-20
Connecting Your Resistor .............................................................................. 3-21
Input Ranges .................................................................................................. 3-23
Optimizing Measurements ............................................................................. 3-23
Auto-Zero ........................................................................................ 3-23
Programmable Ground-Referencing................................................ 3-24
Programmable Open-Thermocouple Detection............................... 3-24
Connecting to External Circuits ...................................................... 3-24
Two-Wire, Three-Wire, and Four-Wire Measurements .................. 3-24
Self-Heating..................................................................................... 3-25
AC Noise Effects ............................................................................. 3-26
Thermal EMF .................................................................................. 3-26
Using the Current Source ............................................................................................. 3-26
Using Digital Inputs and Outputs ................................................................................. 3-27
Connecting Your Digital Input and Output.................................................... 3-27
