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Using the Barometric Pressure Sensor BARO-A-4V


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#1 jhenise

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Posted 16 June 2013 - 09:40 AM

Hello,

I am doing some prototype work with your Barometric pressure sensor BARO-A-4V, for a data acquisition devise that I am building.

http://www.allsensor...-0041-Rev-A.pdf

I am rather new to this type of work so if this question seem naÔve please forgive me.
I am a chemist by trade and a bit of a hack in electronics.

Based on the specs in the sensorís data sheet of nominal output voltage of 0.25 @ 600 mbar and 4.25 @ 1100 mbar I set up a linearization equation from those two points to convert output voltage to pressure: mbar = 0.125(Vout)+0.5688

However the pressure readings I get seem to be low for example I get 988 mbar and expect 1010 mbar.

I am driving the sensor with +5V input voltage.

Am I over looking something?

Do I need to compensate for input voltage or calibrate the sensor against a known pressure to be more accurate?

Please let me know!

Best Regards,
Jeff Henise

#2 LabJack Support

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Posted 17 June 2013 - 09:13 AM

We don't make that sensor, but I see that it has some ratiometric versions and some reference-based versions. If you have a ratiometric version, the output is proportionate to the input, so if your supply voltage is 5% less the 5.0V then the output will be 5% less than nominal. You also need to consider the other possible errors from the datasheet: +/-50mV output voltage error, +/-20mV offset temperature shift, 0.25% full-span linearity, and 1% span shift.

#3 jhenise

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Posted 19 June 2013 - 10:26 AM

Sorry, I know you don't make the sensor, this was a letter to All Sensors that I meant to modify a bit before posting here! I assume then that the best way to get accurate results with one of these is to calibrate it against known pressures and build the required linearization and offset factors into the conversion equation. this sensor seems to track barometric pressure pretty well compared to local weather info on the internet. It is just off on the absolute value. For now I am adding a constant in the conversion to calibrate to internet weather data and this is working well. now to find a real pressure source to calibrate to!

#4 jhenise

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Posted 20 June 2013 - 11:40 AM

I briefly show the BARO-A-4V working with the LabJack-U6 in this video:



#5 LabJack Support

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Posted 20 June 2013 - 12:44 PM

Thanks for the great youtube videos both and:
1. https://forums.labja...topic=6189&st=0

2. https://forums.labja...topic=6188&st=0

this project looks like you are getting some good results and is quite interesting. We can't wait to see your results/finished project.


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