DaqExpress strain gauge readings

[NTEC]

Hi,

I'm fairly new to NI but have some expereince using LabView and DaqExpress. 

I have recently been measuring strain on asphalt material using half bridge1 config. 120 Ohm Gauges, 2.5V excitation, 2.13GF. As I am working with foreign students I have been using DaqExpress as the interface is easier to demo/train on. With the half bridge set up everything was as expected. I then switched over to a quater bridge 120 Ohm Gauges, 2.5V excitation, 2.13GF. When readings of the same material types are compared the quater bridge gives roughly 4 to 5 times higher readings than half bridge. Can anyone suggest why this may be?

Using NI9237 with NI9949 for half bridge, and NI9944 for quater bridge completion!

[YusufD_UK]

Hi,
Thanks for your post.

Please may I ask for more details on the software (including OS and LabVIEW details) and hardware you have?

[NTEC]

Hi,

the OS is Win 10 *64bit

LabVIEW is not installed on the pc as we are using the stand alone DaqExpress software.

Hardware is NI9237 with NI9949 module for half bridge, and NI9944 for quater bridge completion!

[YusufD_UK]

Hi

Please see this article, on strain gauge configuration, if you haven't already.

Measuring Strain with Strain Gages - National Instruments

https://www.ni.com/en/shop/data-acquisition/sensor-fundamentals/measuring-strain-with-strain-gages.h...

See Sections 3 and 4.

Hope this helps.

[NTEC]

Thanks for the link - I will see what effect the sensitivity would have.

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@YusufD_UK wrote:

Hi

Please see this article, on strain gauge configuration, if you haven't already.

Measuring Strain with Strain Gages - National Instruments

https://www.ni.com/en/shop/data-acquisition/sensor-fundamentals/measuring-strain-with-strain-gages.h...

See Sections 3 and 4.

Hope this helps.

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