Hi haizetara,
Firtly, I´d like to indicate you that your board is working fine.
I´ve got a 6008 and I´ve done the same test and it´s normal that your measure isn´t 2,5V or 5V, due to you aren´t doing fine the connection of your signal into your block connector. I guess that you have connected the PIN either 30 or 31 to AI01(pin 5), if you do this connection your signal is floating mode and you aren´t going to measure 2.5 (pin 30) or 5V(pin 31), due to your signal is not referenced to ground. There are two mode to read this signal, either Differential or single ended mode, for that you´ll have to change the connection mode of your signal into block connector.
__Note: Information about single eded and differential mode
http://ae.natinst.com/operations/ae/public.nsf/web/searchinternal/c8156250190a1386862568b000753174
The steps that you´ll have to do for creating a differential/single ended channel with USB-6008 are: (this is optional. If you screw your signal fine and you´re going to work with NI Datalogger, you don´t need to do these steps. These steps -0, 1 and 2- are useful when you program your board either LabVIEW or other programming language)
0. Install NI-Daqmx base
1. Open NI-Daqmx base Configuration Utility (Starts>>All Programs>>National Instruments>>NI-Daqmx base>>NI-Daqmx base Configuration Utility.
2. Create a new task and under Channel list we´re going to create a differential channel, selecting either "Differential" or "Single Ended" on the Coupling field and fill out the rest of the fields. Save and Exit.
Now, you´ll screw, por example, PIN 30 to PIN 2 (AI Channel 0) and PIN1(ground) to PIN 3(AI Channel 4). With these connections your channel 0 is configurated as Differential mode (the negative terminal is referenced to ground).
3. Open NI Datalogger and chose AI Channel 0 of your board and run. Your signal will be either 2.5 or 5V depending your signal source.
Other method to know if your board is measured fine is to use a battery and screw the positive borne to AI Channel 0+ and the negative to AI Channel 0- (pins 2 and 3 of your board, differential mode).
__Info the pinout of your board in
http://www.ni.com/pdf/manuals/371303a.pdf (page 😎
__Info about how programming your board with programming languages (such as LabVIEW)
http://digital.ni.com/public.nsf/websearch/57393FEDF313E99B86256F0B0010AD2D?OpenDocument
__Examples NI-Daqmx base under Starts>>All Programs>>National Instruments>>NI-Daqmx base>>Examples
__Difference between a Static and Dynamic Example for NI-DAQmx Base
http://ae.natinst.com/operations/ae/public.nsf/web/searchinternal/81bfabf907ad65d886256f9a00824fef?OpenDocument
I hope this helps you
Regards
Diego M.
