04-25-2019 12:21 PM
I'm looking to plot a pressure versus position measurement in LabVIEW using a 9229 module. The pressure transducer is of the Honeywell 0 - 2000psi absolute type with a 0 - 10V output. The position transducer outputs 4 - 20mA and its coming from a PLC system. I'm new to LabVIEW and looking for some tips. Is this type of measurement possible using DAQmx and the equipment mentioned? I also have a 9234 module. I found this link and am wondering if this is a good starting point.
https://labviewwiki.org/wiki/Converting_a_Sensor_Voltage_Input_to_Physical_Units
Thanks,
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04-26-2019 03:37 AM - edited 04-26-2019 03:47 AM
For both transducers you need a powersupply (24V?)
The 9229 can do both channels, and yes DAQmx and LabVIEW will easy display an XY graph.
The voltage output of your pressure transducer is one channel
the current output needs to be transformed to a voltage ... ohm law help here, so you will need a stable resistor to convert the current into a voltage. 20mA into 500Ohm results into 10V BUT the 0.2W will heat the resistor, that's why you need a good resistor with a low temperature coefficient. ... Well depending on your uncertainty budget/goal 😉
How dynamic is your setup? Often you will find line hum in your transducer readings, beside of propper cabling (ground loop stuff , etc) it's a good idea to capture more samples and mean over one periode of your line frequency.
04-26-2019 01:09 PM
Awesome, thank you for your input So far I've created a custom scale in measurement & automation, I want the output of daq assistant to run through the scale and output a psi. How is this done?
04-26-2019 02:12 PM
I've figured out the scaling, now I just need to be able to log the data. I've turned TDMS logging on, set the sample rate to 10Hz and sampling size to 3000. Does this mean after 5 minutes I'll have 3000 readings? Why does the excel file show so many groups with 3000 readings after only a few seconds?