Calculate the zero drift and span drift for temperature measuring.

Solution:

• Calculate the zero drift and span drift for temperature measuring.

  Description:
  For Analog Modules, the specs shows zero and span drift. In this document, the Adam-4011D is used an example to show how to calculate the value of drift.
  
  Solution:
  Temperature measurement errors can be caused by issues with Thermal couple accuracy, the accuracy of the AD converter, and/or the accuracy of CJC, as well as the zero drift and span drift. Setting aside the errors that can be caused by the thermal couple, AD converter and CJC, we focus on errors due to the zero drift and span drift.
  
  According to our specs of ADAM-4011D, zero drift is +/- 3 µV/ °C; span drift is +/-25 ppm/°C. Therefore if it is within the range of 80° C (-10 to 70° F), it might yield 288µV drift in total. 228 µV can be calculated as follows:
  Zero drift: 80° C* 3µV / µ = 240µ V.
  Span drift: 80° C* 25 ppm/ µ * 22mV = 44µ V
  
  22 mV is the voltage corresponding to T type TC table mapping to Max/min range (-100 ~ 400° C). It can be calculated as 20.872 mV (400° C) – –3.379mV (-100° C).
  Total drift = 240 + 44 = 284 µ V
  
  From T type TC table, 284 µV can be back mapped to the temperature of 8° C. According to our spec, the testing ambient temperature varying from -10~70° C will yield to 8° C due to the drift error. As a result, the error reading of +/- 4° C from our test should be reasonable and in the acceptable tolerance.