Custom scale inoperative in accelerometer task

I am using a NI 9234 to measure acceleration. In the Acceleration task, I have fixed the sensitivity at 1000mV/g and I am trying to use a Custom Scale to correct for the actual sensitivity of the accelerometer(~10mV/g). The excitation is set to Internal and 2mA. The input is AC coupled. When I run the task, the scale has no effect on the output values. With 1G applied to the accelerometer, the output remains at ~.014G(pk) regardless of whether a Custom Scale is used or not. Is this normal behavior for an accelerometer task?
LabVIEW 2009 SP1
NI-DAQ v9.1.1
Phillip Neir
GM Engineering
Solved!
Go to Solution.

2mA is the lower end of most sensors supply current.... however should work.
When you say you apply 1G, do you mean 1G peak @ say 160Hz? If you apply 1G static you will see only a small signal while the sensor is moved but no static change since the AC coupling (and maybe even your sensor) don't allow static measurements.
A quick coarse check: fix your sensor on a speaker and place a small brass nut on top of the sensor (or nearby) and apply something like 50 to 200 Hz. Slowly increase the amplitude and watch the sensor signal. At an acceleration slightly > 1G the small object will lift off and bounce back and you can see it in your signal (and even hear it , but watching the signal is more sensitive )
Greetings from Germany
Henrik
LV since v3.1
“ground” is a convenient fantasy
'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'

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Hi AYanez!!
Thank you very much for using NI Discussion Forums!! I found a post that deals with the same issue you are trying to solve for your application. It seems that you have to stop the task for the new scaling properties to be applied. Take a look into this thread:
Programmatically applying a custom scale in an active VI
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ApplyScaledLimitsExample.vi ‏23 KB

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Hey!
The error message I get is as follows:
Error -200378 occurred at DAQmx Start Task.vi:4
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Attachments:
test.vi ‏38 KB

Dan,
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************ kudos always appreciated, but only when deserved **************************

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Hi guys,
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Thanks,
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Solved!
Go to Solution.
Attachments:
Current_Voltage_RPM-_sub_VI-1.vi ‏18 KB

You both had me going nuts trying to figure how to get to that property. Basically just right click the DAQmx property node and "Select filter..." . This brings up the "Configure Filter Settings" where I chose 'show all attributes'. I could then get to the AI Custom Scale Name property.
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I'm having a MAX issue I think. I have several tasks configured to run on a CDAQ chassis. Each channel in each task has custom scales defined in MAX. When I run each task in MAX, I get properly scaled values. When I run the same tasks inside a VI, I get junk. As in, the values either aren't scaled or are scaled to something arbitrary. Anyone seen this before? Anything I should check into?
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Attachments:
custom_scale.png ‏53 KB

Hi John,
Thank you for a good description of the problem you are facing, as I understand it you have set up a custom scale but it doesn't seem to be functioning as you expected.
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>>The problem with this approach is that I can't get a reference to the list item that started Task2 to read the Age from the list item.
you can get the related item from task list item to get the main list item.
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My Blog- http://www.sharepoint-journey.com|
If a post answers your question, please click Mark As Answer on that post and Vote as Helpful

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Custom scale inoperative in accelerometer task

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