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80
G
ETTING
S
TARTED WITH THE
CBL 2™ S
YSTEM
© 2000, 2003 T
EXAS
I
NSTRUMENTS
I
NCORPORATED
Set-up
We need to carefully control the variables in the experiment. Watch for light from a
street light or heat from a vent that would change the data. If the equipment is
placed in an external remote location, protecting the unit from moisture by placing
it in a bag might be important, and securing it from theft needs to be considered.
Set up the Sensors
1.
Connect the stainless steel temperature sensor and the TI light sensor to
Channel 1 and Channel 2 of the CBL 2, respectively. Connect the CBL 2 to the
calculator.
2.
On the calculator, run the DataMate program or app.
The CBL 2 automatically identifies the temperature and
light sensors. The DataMate program also loads a default
experiment, but we will change these settings.
Change the Mode
Now we need to select an appropriate data collection MODE for the experiment.
This is an essential part of the experiment design. What makes sense for our
experiment? Do we want to collect a data point every second for 24 hours? Should
we collect 1,000 data points? What are we trying to accomplish with our
experiment?
♦
The calculator has limited memory, so we do not want to collect more data
points than the calculator can handle. On some TI calculators, a selection of
more than 180 points may cause some problems with the analysis. Some good
“rules of thumb”:
−
When using 1 sensor, collect 180 points of data or less.
−
When using 2 sensors, collect 90 points per channel or less.
−
When using 3 sensors, collect 60 points per channel or less.
♦
Additionally, the type of sensor needs to be considered. Collecting data at the
rate of 50,000 data points a second (one reading each 0.00002 seconds) would
be inappropriate for many sensors, as well as being too fast for an examination
of the temperature change as a cold front moves through the area.
For this investigation, we want to collect data every 16 minutes for 90 samples.
1.
After DataMate auto-ID’s the sensors, press
À
SETUP to
enter the Setup screen.