Red Lion LEGEND - Manual (Page 66)

EXAMPLE #2:
A quadrature Rotary Pulse Generator that provides 100 pulses per revolution
is coupled to a feed roll that is 2.5 feet in circumference. It is desired to read in feet
with display resolution to the nearest hundredth of feet (0.01).
In this application, the requirement is for the display to read in hundredths of a
foot. A 2.5 ft. distance equates to 250 “Display Units” (hundredths). The
“Number of Pulses” for 2.5 ft. is 100, as stated. From the information obtained,
the Total Scaling, “K
T
”, can be calculated, using Formula #1.
K
T
= Display Units ¸ Number of Pulses = 250 ¸ 100 = 2.5
With a Total Scaling, “K
T
”, of 2.5, it can easily be seen that for every pulse that
is input, the display increments by 2.5 display units (hundredths). The
application requires resolution to the nearest hundredth of a foot. To get higher
resolution, Quadrature X4 Input Response Mode is selected. This provides four
times the resolution. Using Formula #2, and 4 for the “Number of Count Edges”,
the Remaining Scaling, “K
R
”, is calculated.
K
R
= K
T
¸ Number of Count Edges = 2.5 ¸ 4 = 0.625
At this point, it can be seen that the Remaining Scaling Factor value of 0.625 fits
into the Count Scale Factor value range without losing any significant digits or
scaling it any further. Because of this, the Scale Multiplier (SCM) factory set value of
X1 is used, and 0.6250 is programmed directly in for the Count Scale Factor, “SF”.
SF = K
R
¸
SCM = 0.6250
¸
1 = 0.6250
SCALING FOR TOTAL INDICATION
The Totalizer can be scaled identical to the Process Counter by leaving the
Total Scale Factor at the factory setting of 1.000. To obtain a different unit of
measure (i.e, meters instead of feet, or yards instead of feet, etc.) for the Totalizer,
the proper conversion factor can be programmed for the Total Scale Factor.
Example: A paper manufacturer processes paper by the foot, but also wants to
keep track of the total in meters. All that is necessary is to determine the Total
Scale Factor. To convert from feet to meters, multiply the Total Scaling (K
T )
by .3048 (This is how many meters are in each foot).
FORMULA: K T x SF T = Totalizer Scaling
WHERE:
K
T
= Total Scaling (Process)
SF
T
= Total Scale Factor
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