1.4.1.3.4.2.2.1 How to connect a temperature sensor
There is no particular input for temperature sensors in Node. Four analog inputs are available. Any of
these can be used to measure the temperature sensor resistance. But the single-ended (AI 1, AI 2) is
more accurate than the differential inputs (AI 3, AI 4) because the voltage difference is less. A simple
circuit with an extra resistor for voltage dividing has to be implemented externally. For details about
using temperature sensors please
check our System integration guide
.
1.4.1.3.4.3 Attaching a voltage divider
A voltage divider is needed when the Analog In needs to be calibrated. This is required for adjusting the
measuring range when using a temperature sensor.
The image below depicts how to connect an RTD sensor resistance using the single-ended analog input.
The internal resistance R of the single-ended analog input is 20.4 kΩ and it is connected in parallel to
the RTD sensor.
i
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