© National Instruments Corporation 4-1 SCB-68 Shielded Connector Block User Manual
4
Using Thermocouples
This chapter describes how to take thermocouple measurements using the
SCB-68. A thermocouple is created when two dissimilar metals touch, and
the contact produces a small voltage that changes as a function of
temperature. By measuring the voltage of a thermocouple, you can
determine temperature using a nonlinear equation that is unique to each
thermocouple type. Thermocouple types are designated by capital letters
that indicate their composition according to the American National
Standards Institute (ANSI) conventions. To determine the type of
thermocouple that you are using, refer to Table 4-1. For more information
on the theory of operation of thermocouples, refer to the NIDeveloper
Zone tutorial, Measuring Temperature with Thermocouples, at
ni.com/zone.
Table 4-1. Thermocouple Coloring
Thermocouple
Type Positive C olor Negative Color
Thermocouple
Cover Color
Extended
Grade Cover
Color
BGray Red —Gray
CWhite/Red Trace Red —White/Red Trace
EPurple Red Brown Purple
JWhite Red Brown Black
KYellow Red Brown Yellow
NOrange Red Brown Orange
RBlack Red —Green
SBlack Red —Green
UBlack Red —Green
TBlue Red Brown Blue