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Difference in STEVAL-STWINKT1B Time Domain Analysis output compared with Industrial VibrationMeter

Nikhil D&K

Hello Developers, 

We are currently developing a product for industrial machines condition monitoring and predictive maintenance application. For evaluation purpose we have bought "STEVAL-STWINKT1Bfor the same. We are using the "en.stsw-stwincell" cellular example for publishing stwin's data to the aws cloud. In this example for vibration analysis, on board IIS3DWB sensor is used with default sensor parameters (i.e stated below) and the Time Domain Analysis output (i.e Acc RMS, Acc Peak and Speed Rms) in all 3-axis is published on the AWS cloud after the Time Domain and Frequency Domain analysis has finished i.e after TACQ (5 seconds). And for reference measurements we are using SPM Portable Vibration meter (VIB-15) based on analog sensor, generally used in industries for measurement of  true acceleration and velocity values in 1-axis of machine for condition monitioring. 


Parameters used in Cellular Example:

IIS3DWB Configuration



Effective ODR: 26.9KHz



FFT Parameters:

FFT Size: 1024


TAU : 50

Window: Hanning

TD Analysis: Speed & Accelero

TACQ: 5000 (5 seconds)



Now we have a Compressor/Chiller/Motor equipment in Industry on which we are measuring the Acc Rms and its velocity during its normal working condition.  Now as IIS3DWB sensor is digital sensor it's output is measured in all direction, but we are only taking into consideration the effective Y axis of digital sensor as it aligns with the SPM vibra meter. Now we took readings of Acc Peak, Acc Rms, Speed Rms using both STWIN kit and SPM vibra meter. But the measured reading from the STWIN are drastically different from the vibra meter (i.e almost double at higher vibrations). Also we converted the value of Acc rms into G, as the measured value of acceleration is in G for vibrameter and velocity rms have same unit of mm/s in both devices. 


So i would like to know what could be the issue here as measured values are taken in similar conditions and both devices were well mounted ? Shouldn't STWIN TDM data should match or come nearby the readings of SPM vibra meter ? Or we are doing wrong thing by comparing the analog sensor output with digital sensor output although the end appplication is same.


Reference Links: 

ST Win board:

SPM VibraMeter:



Setup Images for Reference: