3B Scientific 3B NETlab™ - Manual (Page 7)

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• Activate the inputs which are to be triggered at
the left of the box.
• In the middle of the box you can select
whether the trigger should occur when the sig-
nal crosses the threshold rising or falling.
• Trigger thresholds for the analog inputs can be
set on the right (as a percentage of the upper
limit of the input range).
5.1.5 Conducting measurements:
When all settings have been carried out, confirm
and click “Parameters OK”. You can now start
measuring by clicking “Start”.
5.1.5.1 Standard mode:
• If manual recording mode has been selected,
you can make a measurement simply by click-
ing “Sample”. At high -speeds a bar appears
showing the progress of the measurements be-
ing conducted. The display of measured values
is dealt with in section 6.1.8 “Evaluation”.
• Measurements can be stopped before they
have finished by clicking “Finish”. If this is not
done, measurements continue to be made un-
til the desired number of values has been re-
corded. After that it is possible to carry out an
evaluation.
• In order to start new measurements, first click
“Reset”. You will first be given the chance to
save the current recorded values in a new data
record. Thereafter, you can begin conducting
new measurements. In case any parameters
need to be changed, click “Change settings” in
order to return to the choice of inputs. Your
saved settings will not be overwritten by doing
this.
5.1.5.2 Oscilloscope:
A new window opens, consisting of the oscilloscope
display and control panel. It is possible to adjust
the sampling rate and the input range by moving
the corresponding sliders during measurements. In
addition, a trigger is provided which initiates the
recording of the measurements when the threshold
has been crossed. The first slider, marked “Trigger”
in the control panel, is used for selecting the trigger
input. The second slider determines in which direc-
tion the threshold has to be crossed. The third
slider sets the threshold itself, specified as a per-
centage value of the top limit of the input range.
The “Sampling” control panel allows you to choose
between “Single” and “Continuous” modes. If “Sin-
gle” has been selected, the recording of measure-
ments begins when you click “Start” and ends after
one sweep. In this manner, it is possible to trace
rare events as soon as they cause a trigger without
their being immediately overwritten.
The oscilloscope window can be closed by clicking
either of the buttons “Abort” or “Finish and Store
Data”. If you click the latter, the measurements
most recently recorded (128 samples) remain dis-
played in the display mode selected at the top, just
as in standard mode, and are available for evalua-
tion.
5.1.5.3 Datalogger:
In this mode, no measurements are actually begun
after you click “Start”. Instead, a selection window
appears.
Setup: writes the configuration of the inputs and
the sampling rate to the equipment. Once a mes-
sage has been received acknowledging that the
data has been stored, the equipment can be dis-
connected from the computer and can be used as a
portable device for measurements. Additional
information is available in the 3B NETlog™ instruc-
tion manual.
Readout: this opens a second selection window.
Click “Readout” to read data from the internal
memory of the 3B NETlog™ device. “Previous data”
calls up the most recently recorded data. A list
containing the available data records appears, from
which it is possible to select one set of records and
download it by clicking “OK”. Note: the maximum
number of samples read out is no greater than the
value that was specified under “Number of samples”
in the measurement control panel.
5.1.6 Generator:
5.1.6.1 Constant signals and digital pulses
In the course of the measurement process voltage
signals can be output from the analog outputs and
logical signals from the digital outputs. The “Out-
puts” button accesses a menu where you can enter
values for constant voltage at the analog outputs.
For digital outputs, it is possible to choose between
the following options:
0: During the entire measurement process, the
digital output is set to “logical 0” (0 V).
1 permanent: during the entire measurement
process, the digital output is set to “logical 1” (5 V).
1 with delay: the digital output switches to “logi-
cal 1” shortly after the measurement process has
been started.
Pulse with delay: the digital input sends a pulse
shortly after the measurement process has started.
In order to activate the analog outputs, turn on the
check box “Analog outputs ON”.
5.1.7 Signals varying over time (Function genera-
tor):
It is possible to use the function generator to gen-
erate time-variant periodic signals at the analog
outputs using the “Generator” button. The sample
rate for the generator is always equal to the sam-
pling rate of the measurement. If manual recording
has been selected, then the sampling rate of the