07-02-2018 06:05 PM
Hello everybody
I would like to connect a load cell (PT LTd, Universal tension / compression, 10 ton) to my NI CDAQ 9188 through NI 9239, but I have problems when calibrating the load cell, because, there is no variation between the readings recorded (Figure 1) between 1000 kg and 3000 kg. To the load cell I supply 10 V and 0.02 amp with a power source.
07-03-2018 03:10 AM
Use a bridge signal conditioner 🙂
Or a DAQ that is build to read bridge sensors.
You have a 10t sensor, 10V excitation, with 2mV/V sensitivity (=20mV max signal at 10t) the input range from your 9239 is +-10(.52) V fix (and error ranges already near your signal ...) 3t -> 6mV. A gain of 500 (400 with error/overload/drift/offset) would be needed.
However you should be able to see some signal ... if you wired it up correctly.. maybe buried in noise ?
07-03-2018 09:22 AM
Hello, during the calibration apply different forces with a compression equipment and record the data, in the image shows the different variations (Figure 2).
I'm really new to LABVIEW, I only have NI 9239 and NI 9235.
About the noise I have no idea how I could realize
Thanks for your help
07-03-2018 10:38 AM - edited 07-03-2018 10:42 AM
How do you sample ?
Noise: Capture 15000 sample @ 50kHz : Look at the signal in time and frequency domain ..
If you read 10 or 100 times the same load, how does the values look like?
(Read 10000 values at 10kSPS (1s of data) and take the mean value)
It can help if you post your LV code 😉
07-03-2018 12:38 PM
my VI is formed by three instruments (COD GAGE, LVDT and LOAD CELL).
The three instruments are connected to a power source, which feeds them with 10 V and 0.08 amp in parallel.