Configuring DAQ AI Polarity/Range

[aaronSU10]

I am using a PCI 6023E DAQ to acquire voltages from a BNC 2110 Shielded Connector Block.  I need a resolution of 1/100 to 1/10 of a mV, however the current resolution I am getting is 2.44mV.  From the literature I've read (the manual) it seems as though I should be able to use the Measurement & Automation Explorer to configure the input polarity and range and thereby increase resolution, however when I go to Measurement & Automation Explorer (version 2.2.0.3010)>>Devices and Interfaces>>PCI-6023E>>AI the "Polarity/Range" pull down menu only has one option "-10.0V-+10.0V" whereas the manual makes it seem as though there exist various options ranging from +-10V to +-50mV.  Essentially, I need to increase the resoution of my acquired input voltages and am hoping to do so by decreasing the analog input voltage range...am I looking in the right place?  Any suggestions or advice on how to do this?

Thanks very much,

Message Edited by aaronSU10 on 02-22-2007 05:00 PM

[devchander]

One information we will require before telling you how to set the range of an AI channel

In which programming language will you be acquiring from the device

C, CVI, LabVIEW??

[aaronSU10]

LabView 6i

[devchander]

You can set the range of each channel of a DAQ card, on LabVIEW, using 'AI config.vi' in an AI acquisition VI

Look at attached pic

Hope this helps

regards,

Dev

Message Edited by devchander on 02-23-2007 07:09 AM

[aaronSU10]

I believe that I followed the above instructions, but I am still only getting a resolution of 2.44mV and moreover I am still reading in values greater than .5V even when I set the input limits to +-.5V.  Below are links to pictures of the diagram and front panel...maybe you can see what I've done wrong.  Thanks again.

diagram

http://img442.imageshack.us/my.php?image=help1co6.png

panel

http://img85.imageshack.us/my.php?image=help2qk0.png

[Dennis_Knutson]

You've got a 1 and -1 wired to the limit inputs of AI Sample Channel. Putting the AI Config outside the loop doesn't do anything when you reconfigure the limits inside the loop. AI Sample Channel actuall calls AI Config and passes the +1 and -1 values you have wired up.

Even if AI Sample Channel did not call AI Config, putting the AI Config outside the loop and not wiring data from it to the while loop is a bad idea. You have no guarantee that the AI Config would actually be called before the code inside the while loop starts.

[aaronSU10]

How do I enable dithering?

[devchander]

In Traditional DAQ, You use use MIO Configure.vi  to enable dithering (disabled by default) on 12 Bit DAQ cards

Find it at Block diagram>>Functions >>Data Acquisition>> Calibration and Configuration>> MIO Configure.vi

Note: Place it in your block diagram, before AI Config.vi and AI Start.vi

[devchander]

See in attached pic