USB-1208LS with Load Cell (4 Wire)

[chepox]

Do I need an amplifier for the load cell or would the USB-1208LS analog input channels be able to measure the micro voltage changes? 

Below is my wiring. Connecting to the DAQ are AI Channel 0+ and AI Channel 0-. Excitation voltage (5V) is coming from Terminal #30. 

The change in voltage is minimal when load is applied to the load cell. 

 

[DAQman]

Hello,

Take a look at your load cell calibration or specification datasheet. It should list an item called Sensitivity with units of mV/V (millivolts per volt of excitation) and from it you can determine the level of output voltage. Let me give you an example, a sensitivity rating of 3mV/V means that for every 1 volt of excitation, it outputs 3mV when fully loaded. It's quite common for load cells to output small signals. For a case such as this, the USB-1208LS is not the device for the job. My recommendation is  the USB-2408 or to get your hands on a load cell amplifier. The amplifier will supply the excitation and amplify the small signal so that it is large of enough to be acquired by a USB-1208LS.

Best regards,
John

[chepox]

Thank you so much for your response.

I was almost sure of that same conclusion.

I am now acquiring an amplifier that is not a converter so that I can continue to feed into the Analog Channel. Any recommendations on voltage signal amplifiers?

[DAQman]

Dataforth.com sells inexpensive signal conditioner amplifiers. Check out the 8B38-32 https://www.dataforth.com/catalog/pdf/8b38.pdf

You'll need an 8Bxxx carrier board and 5 volt supply. Here's a complete list

https://www.dataforth.com/catalog/pdf/8Bintro.pdf

best regards,

John