7. Viewing Saved Measurement Data
7.1. Graphical Trend Display
The purpose of measuring vibration according to ISO 10816 and ISO 13373 is as
follows; To make assessments concerning the operating condition of a machine
based on changes in its vibration behavior. To achieve this it is imperative, that mea-
surements are taken at regular time intervals, from the same points and under the
same conditions.
To deliver the service staff on site a report about the periodic changes in vibration
severity and consequently the previous history of the measurement point concerned,
the VM22 provides a graphical trend display. The prerequisite for retrieving graphi-
cal trends is placing the sensor on the relevant VMID. The trend display is obtained
by pressing the F2 key. (19).
The vibration velocity is shown on the vertical axis and the time on the horizontal
axis. Both are scaled to their respective maximum value. The time axis shows the in-
terval between the first and last saved measurement. Below the diagram there is a
red marker. This can be moved horizontally to read the magnitude, with the F1 and
F2 keys. The marker only skips forward to time points which already have a measur-
and. At each data point the date and time of the measurement as well as the mea-
sured RMS are displayed. Above the diagram the text assigned to the measurement
point is displayed. In order to be able to display trends, the points are joined to-
gether by a line.
Press the OK key to exit the trend display.
If only one or zero measurands for a selected measurement point can be located in
the memory, the error message “Too few data for trending” will appear instead of the
trend graphic.
Note: The available PC software enables you to view the trends more conveniently,
even without it being connected to the measuring point (cf. Section 13).
14
Figure 19: Trend Display
