Measure a noisy dc voltage with NI6220

[metrologick]

Hello, I just have to measure a 2.5Vdc (output of a hall effect sensor). With a simple voltmeter, as a Agilent 34401A, I can measure eg 2.5162V with a great stability, the last digit doesn't move. With the NI6220, it is completely unstable, the voltage is between 2.47V and 2.55V (a variation of 80mV). Do you have any suggestions to improve this measurment to get a good stability, in fact, how can I ignore the noise on this dc voltage, as the HP34401A or any simple multimeter is able to do it?

Thank you for your help.

[Jun']

Hello Metrologick,

Have you tried using differential measurement?

If this doesn't do, can you check if the impedance is the same? Sometimes you need an impedance converter between systems.

Thanks

M-Junior