I have got a NI 6218 device and I am reading analog signals from its analog inputs. The problem is with small input signals(in the range of 0.217 volts). The device specification mentions that the analog inputs have a resolution of less than 1mV, but in practice when I give a constant input of 0.217V to one of its analog inputs then I have a lot of fluctuation in the acquired data ( the acquired data fluctuates between 0.180V to 0.260V.) does anyone have any explanation for this? Is this device able to acquire small signals with the resolution mentioned in its data sheet?
