Elenco XP&trade - Manual (Page 52)

Project B20 Data Logger with Cost
This program uses the previous circuit, but adds
wattage for the light being measured, cost per
kilowatt hour, and total cost calculations to the
data output. Use the same circuit, and turn on the
slide switch (S1). Load the program “Data Logger
with Cost” into the microcontroller U21 using
instructions in project B1.
The microcontroller measures the time a 100 watt
light bulb is on using photoresistor (RP) at start
up and for the next 6 hours. During this process
the microcontroller calculates the cost based on
12.5 cents per kilowatt hour. Data is sent to the
microcontroller as it is taken and stored every six
seconds in a data memory location. Every 15
minutes a new location is created and this
process continues for 24 locations or 6 hours.
When 24 locations are filled the LEDs flash to
indicate memory is full. Data logger with cost may
be stopped and restarted but data for the
recorded location may be lost.
Access the data using the terminal window as
described in the preceding Data Logger project.
Optional:
-51-
This number sets the cost in
pennies times 10 per kilowatt hour.
12.5 cents = 125.
This number sets the wattage for
the lamp being measured. Range is
10 to 1000 watts.
This line calculates the fractional
penny cost for the time period
displayed.
This line calculates the whole penny
cost for the time period displayed.
This line displays total cost (in
cents) during a data dump.