Custom scale G Force measurement from accelerometer

[KAVIN_GOVINDARAJ]

I need help with my task, so i using kistler  50g its sensitivity is 100mv/g Single axis accelerometer, measurement using NI 9234 module, so question is how can i get G values, there is already a conversion configuration in DAQmx, usually at ground 

it should show 1G, but it shows vibration values and not G values. The experiment is to drop a setup from a high of 50m and measure the G force.
If I should proceed to custom scaling, what values should i give it to the table, i never used custom scale before. 

[Bob_Schor]

Why don't you calibrate your accelerometer?  To do this, you need a stable level platform (put a ball bearing on it and make sure it doesn't roll).

• Put the Accelerometer on the platform with the Axis pointing "up".  Record (with an oscilloscope) the output voltage.  [You want an oscilloscope to be sure you don't have excessive high-frequency "noise" in your signal).  This reading represents 1g acceleration (or -1g, the convention is a bit flexible].
• Now repeat, with the Axis pointing "down".
• Assuming your accelerometer is linear in the -1g to +1g range, solve the equation "Volts = bias + gain * Accel" for "bias" and "gain" (with  your two pair of Volts and Accel readings).

One thing to note -- a 1-axis accelerometer only measures one dimension.  In principle, if you put your accelerometer on a table with the axis pointing horizontally, moving it on the table top should give you no appreciable reading (especially if you move it "smoothly".

Bob Schor

[dsb@NI]

DAQmx scaling for an accelerometer can be configured with the following units:

You do not need a custom scale.

Which model of Kistler accelerometer? If you need to measure gravity, a MEMS accelerometer is recommended. However, the 9234 is designed for dynamic (vibration) sensors. For an IEPE sensor, each 9234 channel provides power (>= 2.0 mA IEPE excitation current) and removes sensor DC bias voltage (using AC coupling filter) so the ADC is not overloaded. The AC coupling filter is specified:

NI does not recommend SV modules for precision DC measurements.