Obtaining data from charge amplifier

[James390]

Hello all,

I am new to LabView and was hoping to get some help with getting data off of a charge amplifier and onto a computer. I am attempting to collect chamber pressure data from a firearm using a Kistler 6215 piezoelectric strain gauge and 5018a charge amplifier connected to the computer via usb. Since I have no experience with LabView, I was using the example "Continuous serial write and read" file to communicate with the system. I have been able to connect to the charge amplifier and change the settings using the command box in LabView so I know I am communicating with my system, but I do not know how to get data from the piezoelectric sensor from the charge amplifier and onto my computer. The dialogue in the response box does not appear to be that of measured data. Any assistance or insight is greatly appreciated.

[GerdW]

Hi James,

5018a charge amplifier connected to the computer via usb.

Unfortunately Kistler requires you to "register and login" to be able to read even the simplest datasheet.

So you need to read those manuals on your own…

The dialogue in the response box does not appear to be that of measured data.

You also hesitate to tell us the data you receive from that amplifier…

What kind of help do you expect with this little information?

[Bob_Schor]

Generally when learning to use a new Computer Language, you first learn the Language and then you start to develop your application.  You seem to be doing this in the reverse order, perhaps because you've been told that "LabVIEW is so easy, you don't need to know anything to begin collecting data".  

This is only 5% true, and only in the very constrained environment of NI Sales Demos where you are provided the DAQ Devices and shown "how easy it is to collect data".

To "do it right", first Learn LabVIEW.  There are tutorials on the first page of this Forum that will get you started.  Pay attention to how LabVIEW works, particularly how it uses Data Flow and "Wires" (which carry data) to do operations sequentially.  Be sure to actually write LabVIEW code as you work through the Tutorials.  If they show you a VI, create it yourself and run it to see if/how it runs.

Once you have some familiarity with the "building blocks" of LabVIEW, learn how to connect with hardware using DAQmx (= Learn DAQmx).  Among other things, this will acquaint you with some of the "technical things" you need to know before talking about "getting data off of a charge amplifier and onto a computer".

Bob Schor

[Henrik_Volkers]

the serial port is for configuration only (AFAIK) , you have to connect the analog output to a data aquisition unit (DAQ) analog input with +-10V range and I wouldn't go below a samplerate of 250kHz (1MSPS if you use the full bandwidth (400kHz) of the CA, but that depends on the sensor used and the low pass filter configured). Your sensors resonance freq is at about 240kHz to 260kHz , so a lowpass filter of 200kHz and 500kSPS would work, but since you want to measure peaks, I would sample with 1MSPS or more.

If you have a digital scope you can use that to (trigger and) sample the pressure peak and use LabVIEW for the scope control and readout. The usual 8bit digitizer isn't isn't the highest resolution, but I wouldn't expect less that 2% accuracy anyway 😉 (You maybe get a traceable static calibration with lower uncertainty, however the dynamic usecase you have is another case)

If you are lucky, you can read out (and reset) a peak value , that should be described in the manual. Since they do a charge to voltage conversion-> AD -> signal processing-> DA  internal anyway, you have a chance to get a peak value. But I assume that you can't get a continous datastream via serial, but no way with a samplerate and resolution you need.

And you can ask Kistler if they have a (official or inofficial) LabVIEW driver for that model.