Using NI DAQmx and USB 6009; starting off with lab view

[manasi]

Hi

I am a pretty new user to NI DAQmx, USB 6009 and labview, so please bear with my question.

I have connected a pressure sensor with i/p 0 to 25 psi and o/p 0 to 10 mV to the anolog i/p channel 4 of the USB 6009. I have installed NI DAQmx 8.0, VI logger and labview 8.2. I tried running the test panels for the USB device, so that I can read the voltage signal from the sensor, as a graph. But there is too much noise and the voltage reading on the graph displayed does not seem to correspond to the actual o/p voltage reading(as the multimeter reads).

Am I on the right track? If so, What am I doing wrong? and Is there a better way to do this?

Also, Please tell me how I could start using labview for such data acquisition applications. Any information would be of great help to me.

Thank you

[RTSLVU]

0-10mV is pretty low value for that device to measure. No wonder you are having noise problems.

I would suggest some signal conditioning like a an op amp circuit with a 100x or 1000x gain.

That would give give you a 0-1 volt range or a 0-10 volt range to measure.


Message Edited by RTSLVU on 02-28-2008 12:16 AM

[manasi]

Thank you very much for the response. I was wondering if using a low pass filter would mean losing some data that we are trying to read. So I thought I could resort to it as a last option. But is there anything else I could do?

Also I have two other questions:

1) On the test panel, the y-axis is labeled as "amplitude". Is there anyway for me to find out if the readings are "Volts" or "MilliVolts" ?

2) Also, the drivers that I installed for the USB 6009 were for windows xp/2000. But I have Vista on my computer. As of now I dont think I have any problems. Do you think I'd have trouble due to the operating system. If so, what could I do about it?

Thank you

[smercurio_fc]

A low-pass filter wouldn't do anything about the signal level. It just clamps down on any high-frequency noise. It would clean up the signal, but it would still be at the same signal level. A signal conditioner that amplifies the signal with built-in filtering is your best bet. If  you don't know how to design one yourself NI has a few offerings, and I will let NI chime in on this.

As far as the amplitude units, the reading you get will be in Volts. You can scale it to be mV, megaVolts, or apply a tranfer function to convert it to whatever unit you want based on what the sensor is.

You said you have Vista. Which version of DAQmx did you install? You really should install a version that has been tested and verified to work with Vista. The DAQmx drivers can be freely downloaded from this site.

You also asked about examples. There are lots of examples that ship with LabVIEW. Just open up the Example Finder (Help -> Find Examples) and go to the Hardware Input and Output category.