Chapter 4 Analog InputNI USB-621x User Manual 4-26 ni.comDIFF input connections are recommended for greater signal integrity forany input signal that does not meet the preceding conditions.In the single-ended modes, more electrostatic and magnetic noise couplesinto the signal connections than in DIFF configurations. The coupling is theresult of differences in the signal path. Magnetic coupling is proportionalto the area between the two signal conductors. Electrical coupling is afunction of how much the electric field differs between the two conductors.With this type of connection, the NI-PGIA rejects both the common-modenoise in the signal and the ground potential difference between the signalsource and the device ground.Refer to the Using Referenced Single-Ended (RSE) Connections forFloating Signal Sources section for more information about RSEconnections.When to Use Non-Referenced Single-Ended (NRSE)Connections with Floating Signal SourcesOnly use NRSE input connections if the input signal meets the followingconditions:• The input signal is high-level (greater than 1 V).• The leads connecting the signal to the device are less than 3 m (10 ft).DIFF input connections are recommended for greater signal integrity forany input signal that does not meet the preceding conditions.In the single-ended modes, more electrostatic and magnetic noise couplesinto the signal connections than in DIFF configurations. The coupling is theresult of differences in the signal path. Magnetic coupling is proportionalto the area between the two signal conductors. Electrical coupling is afunction of how much the electric field differs between the two conductors.With this type of connection, the NI-PGIA rejects both the common-modenoise in the signal and the ground potential difference between the signalsource and the device ground.Refer to the Using Non-Referenced Single-Ended (NRSE) Connections forFloating Signal Sources section for more information about NRSEconnections.
