Peak Value Acquisition

[NI-Joe]

I have this piezoelectric sensor (Kistler 9317B) and amplifier (Kistler 5073 A3 (+/-10 V)) converting the signal to voltages. The sensor only gives the change of electrical charge and I only get a single peak when static load is applied.

When opening the ManuWare program I can change the "Peak Mode" of the Amplifier to "+Peak" and see the static voltage, equivalent to the static force. But when I'm attempting to use NI USB-6008 DAQ, which I prefer, I only get the peak without the Peak mode settings.

I'm far from being a signal expert, but is it possible to do some conversion magics to obtain the static output?

[andmboa7]

Hey @NI-Joe

How are you using the USB-6008. Can you explain your setup with more details?

Are you using a LV program or MAX?

[NI-Joe]

I'm only using Matlab for Data Acquisition. When using the Serial Port to PC and the ManuWare program for the Amplifier, I can read 'correct' data when I've checked "+Peak". I can also use an MCC DAQ and the DAQami software to get the exact same data. But when I'm using the NI DAQ and Matlab I don't get the correct reading.

[Henrik_Volkers]

You read an array of voltages . Now you need the correct scaling and proof it with a calibration. (apply a known force). Check if the output impedance of the amplifier and the input impedance of the 6008 may explain some differences.

Peak values can differ for many reasons:

Too low samplerate of the DAQ (you just missed it)

or

The amplifier internally has a slow sampling unit (some Kistler have a charge amp (CA)-> AD-> DSP->DA structure) and may have a dedicated analog peak hold circuit after the CA to not miss the peak due to the internally too slow samplerate. The manual or a Kistler app. eng. can answer that question.