Hello amaka,
The measurement acquired on the analog input channels should reflect the voltage connected to those channels. One thing you will need to consider is the method by which you are connecting your channels. Different connections can result in different readings depending on noise and ground loops. For more information on these considerations, I would recommend that you examine
this document regarding Field Wiring and Noise Considerations. Another troubleshooting step that you could consider would be to measure a battery. This would give you a known voltage level that you could compare to your measurement.
Matt Anderson
Hardware Services Marketing Manager
National Instruments
