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Datasheets and User Guides

Software & Driver


14.1.6 Resistance [T-Series Datasheet]



This Resistance Extended Feature will calculate the resistance of a given circuit element.


To configure, write to the following registers.

AIN#_EF_CONFIG_B - Excitation Circuit Index: The index of the voltage divider excitation circuit to be used.

See Excitation Circuits for circuit indices.

AIN#_EF_CONFIG_C - Excitation AIN Channel Number: The AIN channel number of the AIN line used to measure the RTD's excitation.

Ignored if the Excitation Circuit Index does not use a second AIN.

AIN#_EF_CONFIG_D - Excitation Detail Volts: The number of volts provided as the excitation circuit voltage source.

AIN#_EF_CONFIG_E - Excitation Detail Ohms: The resistance in ohms of the shunt resistor.


The normal analog input settings are used for negative channel, resolution index, settling, and range.


For results, read the following registers.

AIN#_EF_READ_A: Resistance
AIN#_EF_READ_B: Voltage
AIN#_EF_READ_C: Current

Only reading AIN#_EF_READ_A triggers a new measurement.


An unknown resistor to be measured (a 10 kΩ resistor is used in this test) is connected in series with a 200 µA current source.

AIN0_EF_CONFIG_B = 0   -- Excitation circuit 0 (200 µA current source)

Reading results:

  • AIN0_EF_READ_A returns 10089.7 Ω
  • AIN0_EF_READ_B returns 2.012 V
  • AIN0_EF_READ_C returns 199 µA