3B Scientific 3B NETlab™ - Manual (Page 21)

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can also be assigned to one of the measured values
(x-y display).
Modify scale range: use “Autoscaling” to
scale the highlighted axis so that it is possible to
view all data. “Manual scaling” opens a dialog box
in which the limits of the visible intervals can be
entered manually.
Modify time scale range: (exception: in x-y
mode, both of the axes are set in the dialog box
described above)
Fit to a function (Fit): for further information
see the following section
Calculate tangent: if this icon is activated,
then a tangent is drawn to the displayed curve
from the last cursor to be moved If several curves
are visible, then it is necessary to select one of the
curves in a selection window before proceeding.
The section of the axis and the gradient of the
tangent are displayed in the upper left of the
graph.
Calculate integral: when this icon is acti-
vated, it is possible to calculate the integral of the
highlighted (or the only visible) data curve within
limits defined by the cursors. In graphical terms
this corresponds to the area below the respective
curve (which is shaded). Any areas below the x-axis
are considered negative.
Edit text labels: activating this icon allows us
to create a text field and position it on the graph.
5.1.8.3 Fitting to a function (Fit):
Proceed as described in the following to fit a func-
tion to a data curve:
• Click the icon for the graph. A dialog box
for fitting the function will open.
• On the left, select the desired data.
• Click “Edit fit function for selected quantity”.
A window appears in which the section of the
curve that was highlighted earlier by the cur-
sors is drawn (preview) and a list of functions is
presented.
• Select the desired function from the list or
define a unique function by means of “Edit the
user formula”. (See section 6.1.3 “Formulas”. It
is possible to use six parameters from A to F.
The independent variable appears last in the
list.) The equation (strictly speaking, the right
hand side of the algebraic equation) of the
chosen function is displayed above the list.
• Specify the parameters for the initial values on
the right hand side. This is not always neces-
sary. Sometimes, however, the preset initial
values are not helpful. Click “Draw” to plot the
function with the specified parameters in the
preview.
• In addition to the input fields for the initial
values, activating the check box can cause the
parameter values to remain constant during
the fitting of the function.
• Click “Try to fit”. The result is displayed in the
preview. The correlation coefficient R
2 is output
above the control panel labelled “Parameters”.
• After clicking “OK” and exiting the window for
fitting the function, the fit function is also plot-
ted on the graph.
An existing fit function can be edited in the same
way. In order to display or hide a fit function, open
the dialog field for setting a fit function and, after
highlighting the relevant data set, click the corre-
sponding icon.
5.2 Experiments (according to the instructions):
The only difference between experimenting accord-
ing to instructions and experimenting with the
measurement lab is that the control panels have
been incorporated and pre-configured in the ex-
periment procedure. Usually, only those measure-
ment functions which are significant are activated.
In this way, even users little accustomed to the
functions of 3B NETlog™ are able to perform ex-
periments easily. To begin an experiment, proceed
from the splash screen as follows:
• Select “Experiments” and click “Continue”.
• Choose “Perform/browse an experiment” and
click “Continue”.
• Select an experiment from the list and click
“Continue”. The experiment which is now visi-
ble is recognised by the measurement labora-
tory. This is where the data pertaining to the
selected experiment are administered. Subse-
quently proceed as explained in section 6.1.1.1
“”.
6 Administration and network set-up
The functions of 3B NETlab™ described in the fol-
lowing section support its operation within a net-
work. After installation, no administrative interven-
tion is required for single-user operation. Owing to
the innumerable ways of implementing a network
and the corresponding differences in configuration
associated with that, it is not possible to explain
the various steps in detail within the scope of this
chapter. Administrator rights are essential for set-
ting up a network.
The network functionality makes it possible for
instructors to observe students’ experiments from
their own computer while they are being con-
ducted and also to view the recorded readings.
Likewise, instructors can also conduct an experi-