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Hall effect sensor to RPM

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That temperature sensor should be ok to be measured by that cheap DAQ. However I never worked with load sensors. Can you specify your model? I have found this white paper: http://www.ni.com/tutorial/7138/en/

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Hi belae,

 

The load cell's output however is rated in mV/V. How would I determine if the output is too small for the DAQ to read in?

- An output rating of "mV/V" is typical for bridge-type sensors (full bridge, Wheatstone bridge). For each volt of the supply voltage you get "x" mV per unit of the measured physical property.

- Usually you will find additional ratings describing the maximum supply voltage so you can calculate the maximum mV output per unit of your measured property.

- Now you need to know the resolution you want to achieve in your measurement to calculate the resolution you will get in the output voltage of your bridge-type sensor: (min resolution of measured property) * mV/V * (supply voltage)…

- As the resolution/accuracy of the USB6001 is known you can use the same formula to calculate the load resolution you can achieve and compare it with your requirement sheet…

Best regards,
GerdW

using LV2011SP1 + LV2017 (+LV2020 sometimes) on Win10+cRIO
Message 12 of 16
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Hi Blokk, thank you for the link. The device they recommend using for the load cell measurement is out of my budget unfortunatley but it provides good information on load cell DAQ implementation. 

Here is the load cell I will be using; http://www.vishaypg.com/docs/12059/620.pdf

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This is the exact load cell I plan on using, it is equivalent to the model 620 I just sent you ;

 

 https://www.amazon.com/Keli-Electric-S-Type-Hanging-Capacity/dp/B005FA5J2O/ref=pd_day0_229_5?_encodi...

 

Here is a product description;

" Specifications: Sensitivity = 3.0 +/- 0.003m V/V Total error = +/- 0.03%FS Creep (30 min.) = +/- 0.03%FS Zero Balance = +/- 1% FS TCO = +/- 0.03%FS/10 degrees C TC Span = +/-0.03%FS/10 degrees C Input Impedance = 400+/-20ohms Output Impedance = 352+/-3ohms Insulation Impedance = >/-5000Mohms Temp Range, operating = minus 30 to +70 degrees C Max safe overload = 120%FS Ultimate overload = 150%FS Excitation recommended = 10-12V DC Excitation maximum = 15V DC Protection Class = IP65 "

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Thank you for the information. Looking at the USB 6001 specifications, it has a +5V power source through USB if I understand correctly. My load cell will need 10V excitation. I think it is safe to assume that I need to externally power my load cell. My question is, is there perhaps a different USB DAQ I can use that can provide the 10V excitation? I imagine that 5V is all that can be provided through USB, but perhaps there is a DAQ out there can both plug into USB and also into a wall outlet to provide enough exitation for the 10V needed by the load cell? What do you think?

 

Thank you

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Accepted by topic author belae1ka

Hi belae,

 

My load cell will need 10V excitation. I think it is safe to assume that I need to externally power my load cell.

Why do you think so?

The "10 to 12V" is just a recommendation! You can safely power your sensor with just 5V…

 

- The more interesting fact is the current your sensor will draw: Usupply/400Ohm! With 10V you need to supply 25mA, with 5V only 12.5mA. Your USB6001 should be able to supply such current out of the 5V supply pin…

- Another fact is the stability of the power source: any change in supply voltage willl have immediate effect on the accuracy of your measurement!

 

Based on our questions I REALLY recommend to read a book on (basic) electrical measurements…

Best regards,
GerdW

using LV2011SP1 + LV2017 (+LV2020 sometimes) on Win10+cRIO
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