9
CALCULATING SCALE FACTORS
There are two separate dividing scale factors, one for input "A" and one for input "B". The factor to enter is the number of
pulses per the desired unit of measurement. The factor ranges from 0.0001 to 99999. The factor is the same for rate and
count on input "A". Because the "units per second", "minute", or "hour" are field programmable from the keypad, scale
factor calculations for the ratemeter are easy. Here are some examples:
SCALING FACTOR EXAMPLES:
BATCHING
:
You want to count the number of batches (10 boxes each) being loaded onto a pallet.
Solution
- Dial in a scale factor of 10.
UNIT COUNTING:
You pick up a notch on a paper roll (1 pulse per shaft revolution). Each revolution equals 3 feet. To
find the number of pulses per foot, simply divide "1 pulse" by "3 feet" (1
÷
3 = .3333).
Solution
- One foot equals 0.3333 pulses, enter this as the scale factor and the display will read in feet.
RATE
: The shaft of a motor has a flywheel with 10 spokes. A prox switch is mounted to sense 10 pulses per revolution.
RPM of the shaft is the desired readout.
Solution
: Enter a Factor of 10 and for every 10 pulses, "1" will appear on the display. Set rate per
second, minute or hour as desired.
A conveyor carrying bottles must be controlled for bottle speed. For each revolution of the front roller, three bottles
travel by. Thus, one revolution equals 3 bottles. A wheel with seven spokes is mounted on the roller. The user
can't sense bottles because they are traveling through a washer, so a sensor is placed at the roller, sensing seven
pulses per revolution of the shaft, which equals 3 bottles per revolution.
To calculate the scale factor (7 ppr
÷
3 bottles) = 2.3333 scale divider. Set rate per second, minute or hour as
desired.
A flow meter is generating 52.6 pulses per gallon. The desired readout is in liters. Since there are 3.785 liters per
gallon, divide 52.6 by 3.785 to find the number of pulses per liter (52.6
÷
3.785 = 13.897).
Enter 13.789 as the scale factor so the display will read in liters.
An aluminum sheeting plant has a cut to length application to customer specification. A ten pulse per revolution
encoder with a 12" wheel is used to sense. The travel of aluminum sheets is in inches. Thus, after 10 pulses, you
want 12 to appear on the display. Thus, 10
÷
12 = .8333. Enter .8333 as your scale factor.
