PC Vibration Measuring System VibroMetra Frequently Asked Questions
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| How does
VibroMetra licensing work? |
VibroMetra
uses license key files which are activated by right mouse click on the
respective channel of the "Measuring Channels" in the main window. A
license key is valid only for one particular channel of a M302
or M312 IEPE/USB interface with a particular serial number. This information is
needed when you order a license key. For each software instrument
(VM-METER, VM-SCOPE etc.) one license per channel is required, i.e. for
a triaxial instrument, like VM-STRUC, you
need three licenses. For more than one channel we offer quantity
discounts. The license key is stored inside the M302 so that it is
independent of the PC where you run VibroMetra. The licensed
instruments are available as soon as you connect your M302 to a USB
port. |
| How can I test VibroMetra? |
On our download page
we offer a free trial version of the VibroMetra software. This is the
full software package including all instruments. Start the program as
"VibroMetra Simulator". Instead of connecting the M302 or M312 hardware you may use simulated
signals. The simulation menu opens after a right mouse click in the
measuring channels window. |
| Can I calibrate VibroMetra? |
Yes.
The system includes a calibration function which allows to calibrate
the entire measuring chain from the sensor to the display in one step
using a vibration calibrator.  |
| Can the system be operated
for a longer period on an unattended PC? |
Yes.
VibroMetra software is characterized by high stability. Particularly
suited for long-term measurement are the instruments VM-PLOT and VM-REC.
VibroMetra systems have been running in industrial environments for
several years without interruptions. Even after an abnormal system end
the measurement will proceed normally. All you need to do is putting a
link to VibroMetra into the autostart folder of your PC and selecting
the check boxes "Save settings at end" and "Restore sensor connections"
in the Workspace settings of VibroMetra. |
| Why do I get unstable or
too high results when I measure displacement? |
Set the high pass filter
to at least 3 Hz, to suppress low frequency noise. Low frequencies are
amplified by the integrators. |
| How can I export measuring
results from VibroMetra into other software? |
To
make VibroMetra as stable and simple as possible we decided
to limit the number of export formats to a minimum. Most instruments
with graphical output feature an export function for the graphics as
Bitmap, EMF or text file. VM-REC records the measured values on hard disk which allows to process them later by external data analysis software, for example FlexPro. The logger data can be exported either as binary file or in text format. The raw data recording function of VibroMetra Online also offers export capabilities. Load the recorded raw data file (*.ids) into VibroMetra Offline and export is to a text or binary file. For this purpose the options VM-TXT or VM-BIN need to be installed. |
| How can VibroMetra display
time graphs of vibration signals? |
Slow changing vibration
signals may be recorded as RMS or peak values by VM-PLOT
in the way a strip chart recorder does. Real-time recording of the
instantaneous value for short vibration events can be performed using VM-SCOPE. |
| Can I use VibroMetra on
several PCs even if I have only one software license? |
Yes. The software key is
installed inside the M302
or M312 hardware and will be recognized by the system as soon as you plug in
the device, provided the VibroMetra software was installed. |
| How many M302 units can I connect to one
PC? |
Tests have been made using
up-to-date PCs with up to 20 M302
devices, i.e. 40 measuring channels. Several instrument windows can be
opened for each measuring channel without data loss or delay. Such
multichannel systems are set up with active USB hubs. |
| How does
offline measurement work? |
VibroMetra can save the
real-time signal of the M302
or M312 on hard disk. You only need to enter a file name and to activate
a check box in the VibroMetra main window. After switching on a
software
instrument, VibroMetra will save the raw signal on hard disk. This
happens in the background while you measure as usual. To recall stored data, start "VibroMetra Offline".  You will see a time bar graph for each channel that was saved. As known from other play-back devices you will find the buttons play, fast forward, rewind and stop. After clicking the play button, all activated software instruments will start measuring with the data from hard disk. |
| Does the M302 measure with the full sampling
rate when both channels are active? |
Yes. Both channels are
sampled with 10 kHz and have a bandwidth of 2 kHz. |
| Are there M302 or M312 drivers for other software? |
No. |
| The rotary speed detection
of my VM-BAL does not work reliably at
higher speed. No rpm value is displayed. |
The photoelectric reflex VM-PS
switch needs for detection a certain pulse length. If the reflective
sticker is very small, the impulse duration may be too short. Use a
longer strip of the material to cover a larger portion of the rotor
circumference. |
| My photoelectric reflex
switch does not work. VM-BAL does not display
the rpm value even if the LED of the VM-PS
sensor flashes. |
The
power supplied from your PC via the USB interface may be too low. This
problem so far only occurred when a USB extension cable was used and
the cable resistance became too high. |
| I want to see low
frequencies in high spectral resolution but also observe higher
frequencies. Why does VM-FFT not have a
logarithmic frequency axis? |
An
FFT produces equidistant spectral lines. If you plot them
logarithmically, only few lines will appear in the range of lower
frequencies. The upper frequencies are displayed in high resolution.
The a.m. problem can be solved much better by means of the Clone
function: - Display the entire frequency range in one VM-FFT window - Open a second window by the clone function - Display the lower frequency range with high resolution in the second window. |