  
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
M312B 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
M312B 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.
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| 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
M312B 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
M312B 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
M312B drivers for other software? |
No. |
| Why is only one
M312B sending data? |
If you want to measure with
more than one M312B you need
to interconnect them by synchronization cables VM-SYNC. |
| Why does data acquisition stop
sometimes? |
Your system may be overloaded.
Please check the CPU load indicator in VibroMetra Online. If
it shows over 100 % you should reduce the display refresh rate
in the "Displaying" menu or close some instrument windows. |
| 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. |