red lion C48C, Instruction Manual

Page: 49 / 56

The C48C is factory set to provide one count on the display for each pulse
that is input to the unit. In many applications, there will not be a one to one
correspondence between input pulses and desired display units. In these
applications, it will be necessary for the C48C to scale or multiply the input
pulses by a prescaler to achieve the proper display units desired (feet, meters,
gallons, etc.).
The first step in determining the prescaler is to obtain the Number of Pulses
per Display Unit. This may require a small amount of deductive reasoning.
Example : A 48-tooth gear is mounted to a 2 ft circumference feed roll in a paper
processing plant. It is desired to display the footage of paper processed per
day. In this example, the display units are in feet. A sensor sensing the gear
teeth provides 48 pulses for each revolution of the feed roll. Each revolution
equates to a linear distance of 2 feet. The number of Display Units desired is
2. The Number of Pulses per Display Units is 48. When the number of
Display Units and the Number of Pulses have been obtained, the prescaler
can be calculated.
The Prescaler is obtained by dividing the Display Units by the Number of
Pulses as shown in the Formula below.
Prescaler = Display Units x Display Decimal Point
Number of Pulses
For the preceding example, the prescaler is calculated by plugging 2 and 48
into the formula:
Desired Decimal Point Enter In Formula
0 1
0.0 10
0.00 100
0.000 1000
0.0000 10000
0.00000 100000
Prescaler = 2
48
Prescaler = 0.041667
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APPENDIX “D” - CALCULATING THE PRESCALER
WHERE:
Display Units =
Display Decimal Point =
Number of Pulses =
The desired Display Decimal Point position.
The number of pulses required to achieve the
number of Display Units.
The number of desired units (revolutions, feet, 10ths
of feet, meters, etc.) that would be acquired after the
Number of Pulses has occurred.