Measuring data from Baratron through Signal Express using NI C-DAQ 9174

[vmn]

I am trying to read pressure measurement at a point from  a pitot tube using Baratron, which is connected to the NI C-DAQ9174 and to the computer.

I am trying a find a relationship between the acquired values of voltage and the reading from Baratron.

Is there any possibility of displaying the absolute values which is being displayed on the Baratron directly to the computer which later can be exported into excel?

Thanks

[Zach J]

Hi vmn,

Are you looking to read in the same values displayed on the Baratron?  If the Baratron is capable of outputting that signal, you should not have a problem.  I would consult the operations manual for the Baratron to see what it is capable of.  If you are able to output that signal, your cDAQ, if it has the correct type of input modules attached, should be able to read it.  You can then use various methods for writing the data to a file.  What modules do you have on your cDAQ-9174?  What model is the Baratron and do you have the user manual for it?  

[vmn]

Hello,

I have NI 9234 module and a MKS Baratron. I have been working on setting scales to be able to read the data from the baratron. However I am not able to figure it out, i have tried various combinations but still not able to understand. The baratron power supply output is +or- 15 volts. The reading displays as TORR.

Thanks

[Zach J]

What model is the Baratron?  MKS has quite a few models and I would suspect that each one has it's own calibration.  I think what you will want to do is see if the Baratron manual for your device has any information about scaling in it.  For example, the Baratron itself is reading in a voltage and converting it to Torr.  If the manual for the Baratron has any calibration information, you can definitely set up a scale in LabVIEW SignalExpress to convert the voltage to Torr.  If the Baratron manual does not list this information, I would contact MKS to see if they can provide it.  If not, you may have to perform some measurements with known pressures to determine the voltage that corresponds to a given pressure.  

In SignalExpress, you can create a custom scale by completing the steps listed in the following document:

How Do I Create a Custom Scale in LabVIEW SignalExpress?

[sth]

First off the NI 9234 has an excitation current.  I believe that is not what you need and I assume you are powering the baratron from an external ±15 volt supply.  Make sure that the excitation is off from the NI 9234.

Measure volts which should be a sensible number, the baratrons come in 100 mbar, 1000 mbar, 10,000 mbar and similar torr ranges.  All you need is to take the 0-10V signal from the baratron and multiply it by the range stamped on the side of the sensor head and divide by 10V.

Or if you use scaling in MAX then for a 1000 mbar head use a scaling of 100 mbar/volt.