Simple Load Cell Measurement with the USB-2408 DAQ device

Learn more at: bit.ly/O37NLK
Hello, today I am going to measure weight using the USB-2408 from Measurement Computing (MCC) and the LCF450 load cell from Futek.
The load cell is rated to handle up to 250 pounds and to simulate a load I will use a Clamp to squeeze it.
For this load cell, the calibration information is listed here and states a max weight of 250 pounds and a sensitivity of 1.9027mV per Volt of excitation. To determine the maximum output signal, multiply the sensitivity times the excitation voltage. I will use these values a little later to scale the data to pounds.
This load cell has 6 wires:
Red and black are the plus and minus DC power.
Green and white are the plus and minus signal output
And orange and blue are the sense lines.
What they do is supply a feedback voltage to compensate for IR drops over long wire runs. For short wire runs they are not needed and will not be used.
Connect the Red lead to +5 and the Black lead to ground.
Now connect the signal wires. You may have notice a couple slides back that the sensitivity was negative. To get a positive signal I will flip the signal wires. So white connects to the H terminal and green to the L terminal. Now we begin with software
Run the InstaCal and add the USB-2408 to the setup. Next, set the Sensor Category to voltage and the Connection Type to differential. Set the data rate to 60Hz -- this will act as a 60Hz filter reducing noise. And close the InstaCal program
Start the TracerDAQ Pro software and choose the Strip Chart
If this the first time running TracerDaq it will default to four channel -- we need only one.
Now, Change the units to LBS and tab over to scaling. Here check the enable scaling option.
Now I need to scale the output signal to pounds. To do this take the sensitivity number and multiply by the amount of excitation. I'm using 5 volts so the maximum signal is 9.514mV. Next, divide the maximum load by the maximum signal. This yields a scaling factor or 26277 lbs per volt or looking at it another way 37.3uV per pound.
1. Enter 26277 in the Multiplier box
2. Next, go back to the DAQ Hardware Settings, select the device and set the range to the lowest available. Channel zero is automatically populated...
3. Next set the channel display lanes 1. Set the Units to LBS for pound, the Upper Limit to 250 and Lower Limit to zero.
4. Reduce the sample rate to 10 per second.
5. Enable the Measurements windows for numerical values
6. Now Start Logging. I will tighten and loosen the Clamp to simulate load
7. Now Stop Logging.
8. The Measurement View displays the Max, Min, Mean, Current Value
9. Finally, Save the data to CSV file then load the CSV data in Excel.
That's all there is to it! Thanks for watching! Visit our website (www.mccdaq.com) for more information about Data Acquisition devices and the software that controls them.
Learn more about the USB-2408 from Measurement Computing at: bit.ly/O37NLK