Each electronic instrument has an insolation category that can be measured reliably up to a specific voltage. For NI devices, they are classified as insolation level categories 1 to 4. Most NI hardware has an insolation rating of Category 1, and Category 2 or 3 if it is higher. The criterion for this insolation rating is how much element can withstand the magnitude of the earth potential reference voltage. Category 1 refers to a potential within 100 V, and Category 2 refers to a potential range near 220 V, an AC commercial power source. The higher the insolation rating, the less the insolation breaks, so you can safely proceed with the measurements.
In terminal configurations of DAQ device, Differential and NRSE modes require bias resistor(R). See this document for detailed configuration instructions. (Difference Between Differential, RSE, and NRSE Terminal Configurations )
Refer to this document for detailed size configuration of the bias resistor. (How to Select Bias Resistors)
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