I have been using these modules to monitor 4-20mA signals from installed transducers and have discovered that these modules were interfering with the applicable transducer circuit i.e. creating false signals to the installed cct's (my input module was in series with the current loop). Now the signal as seen through my DAQCard 6062E was very noisy with large excursions in levels (300-400% of the actual level) despite the fact that the current loop (as measured with a multimeter) was rock solid.
Unfortunately this seem like a question to ask by phone, because we need a more extensive troubleshooting and understanding (www.ni.com/ask) as far as meantime suggestions you can re-check that in your Daqcard you have your channels set as Non referenced single ended (NRSE). Also check your cable and pin connections, a bad cable or pin may cause this kind of "out of normal noise levels". Farther than that with this information we cannot come up with something else, please give us a call to extend the troubleshooting for this.
Nestor Sanchez Applications Engineer National Instruments