Continuous acquisition using Agilent U2356A and Labview

[krazyups]

Hello,

I am trying to get the continuous acquisition example found in the Labview driver for the U2300 series to work correctly, and I'm having some difficulty.  Basically no matter what setting I try, when I go to read the waveform, it always outputs half of what my measurement range is (ie, 5 if the range is 10, 2.5 if 5, etc).  I am currently just inputting a 1.0Vdc signal into the unit, and when I use the meas? (@101) command, I will get an output of 1 volt, however it is approximately 1 out of every 6 or 7 measurements that are correct.  Mostly I get values close to 0, or NAN, even though my range is set to 5.

I have the latest firmware in the unit, and I'm using Labview 8.5.  Any help would be appreciated, this is driving me nuts!

Steve

[krazyups]

Hello,

It turns out that the DAQ is spitting out ASCII code, and the Labview program is thinking that it is hex, so it is trying to convert it to a decimal number, obviously to no avail.

Does anyone have a handy ASCII to hex conversion VI that I could incorporate into my program, or know where I could find one?

Thanks in advance.

Steve 

[krazyups]

Never mind, I found the string to byte array modifier, now I just need to sort out some other things ...

And I sure do like talking to myself 

Steve

[NathanT]

Hello Steve,

      Could you please tell me which version of the LabVIEW Instrument Driver that you are using?

Thanks,

NathanT

[krazyups]

Hi Nathan,

I'm using the driver that was updated on May 27, 2009.  It's a very strange problem, it doesn't seem to matter which signal type I choose, differential, referenced or non-referenced single ended when I have the signal differentially going into channel 1, it just doesn't want to give me reliable results.  All I'm doing is hooking channel 1 up to a DC power supply and setting the voltage to 1.0 or 2.0 Vdc, I have my range set to 5V.  It should be relatively straightforward, I can't seem to figure this out.

Thanks for the reply,

Steve

[Dennis_Knutson]

Have you been able to perform a successful measurement manually? Separate the driver from the hardware and try to isolate where the problem is.

edit: Sorry, just realized that it has no front panel. It does come with software from Agilent. You could run that and see if the problem happens with thier software.

Message Edited by Dennis Knutson on 06-15-2009 10:26 AM

[NathanT]

Hello Steve,

      I think that Dennis's suggestion of using the Agilent Measurement Manager software is a great idea.  Also it would be good to triple-check the connections and settings of the device.

Cheers,

NathanT

[krazyups]

Hi Guys,

I do know for a fact that Measurement Manager does work properly, and that's part of what makes it so frustrating, I can setup the channels however I want in Measurement Manager and it works properly, but if I don't do anything but change to Labview (or the Agilent VEE software, I've had the same problems there as well) then it doesn't work properly.

I've been in contact with Agilent support, and they haven't been able to solve the problem for me yet.  As an example, they gave me a small piece of code to try with the Agilent Interactive IO, something like this (I might not get it exactly right, I'm at home this week, so please bear with me!):

VOLT:RANG 10

VOLT:POL BIP

VOLT:STYP DIFF

MEAS? (@101)

And with these steps (inputted one line at a time, obviously), along with a constant 1.0Vdc on channel #1 in differential mode, I get a reading of 999.9, which indicates that it is out of range, but it's not!  If I do get a reading, it's usually between 50 - 60mV, and every once in a while it will read bang on.  I can't think of any further information to give you right now, I'll be sure to post when I do.

Thanks for all the suggestions,

Steve

[NathanT]

Hello Steve,

        One more thing to try is making sure that the device's firmware is up to date.  Maybe this problem is caused by the firmware and the Measurement Manager took that into account before the firmware was fixed.

Thanks,

NathanT

[krazyups]

Hi Nathan,

Thanks for the reply.  That was actually the first thing that I did, my firmware is updated to the latest one availble from the Agilent website.  I was having quite a few additional problems before the update!

Steve