Why do I receive error -201171 when measuring my thermocouples?

Updated Feb 11, 2020

Reported In

Hardware

  • E-Type Thermocouple
  • T-Type Thermocouple
  • J-Type Thermocouple
  • K-Type Thermocouple

Driver

  • NI-DAQmx

Issue Details

I am using thermocouples for my temperature measurements using DAQmx. When I am setting the range of my measurements I receive the following error: 
Error -201171  occurred at Property Node DAQmx Timing (arg 1) in Thermocouple - Continuous Input .vi

Possible reason(s):
Minimum temperature specified for the thermocouple measurement falls outside of the accuracy limit when using polynomial scaling.
Specify a value greater than the minumum temperature for  polynomial scaling with this thermocouple type, or set the Thermocouple Scale Type property to Table

As viewed in the following image:




 

Solution

DAQmx has the ability to choose between two scale type when setting up your thermocouple. The two options are Polynomial and Table. This allows the user to essentially choose whether to use the inverse or regular coefficients. The default is to use polynomial scaling.

The ranges of each scale type for all supported thermocouples are detailed in the table below
 
Thermocouple TypePositive ConductorNegative ConductorRange for Table Conversion (°C)Range for Polynomial Coefficients(°C)
JIronConstantan-210 to 1200-210 to 1200
KChromelAlumel -270 to 1372-200 to 1372
NNicrosilNisil-270 to 1300-200 to 1300
RPlatinum -13% RhodiumPlatinum-50 to 1768-50 to 1768
SPlatinum -10% RhodiumPlatinum-50 to 1768-50 to 1768
TCopper Constantan -270 to 400-200 to 400
BPlatinum Rhodium0 to 1820250 to 1820
EChromelConstantan -270 to 1000-200 to 1000

To change between one scale type to the other, see the Knowledge Base article Thermocouple Input Task Scale Type Property in DAQmx