SCALE FACTORS
29
must be made since the scale factor is dis-
played in the X.XXXX format. The display
shows the value as each key is pressed.
5. Press the “ENTER” key to store the new data.
The display blanks momentarily as the control
stores the information. If a zero is entered as
the Scale Factor, the counter defaults to the
value of 1.0000.
6. The next function to be interrogated or modi-
fied may be specified. If no additional functions
need to be selected, the counter may be
returned to displaying the current count value
by pressing the “COUNT” key.
COUNT SPEED VERSUS SCALE FACTOR
The scale factor entered into the counter has a
direct effect on the maximum rate at which the
counter can receive count pulses. Generally, the
larger the scale factor the slower the counter can
receive pulses. A table indicating count speed ver-
sus scale factor values is given in Figure 23.
In this table, the Normal Count columns represent
the speed at which the counter can receive pulses
when it is operating in the Add/Subtract, Count
with Direction Control or Count Up with Inhibit
Control modes. The Quadrature and Doubled
Count columns indicate speed whenever the hard-
ware doubling (jumper installed between the Dou-
ble Input and DC Common) is utilized.
OPERATION OF THE SCALER
When the counter receives a count pulse, the
scaler recognizes that fact and multiplies the 1
pulse by the scale factor. The scaled value, which
will be a number from 0.0001 to 9.9999 since this
is the range of the scale factor, is added to a
resultant total. This resultant is shown on the dis-
play. However, the result can have up to four deci-
mal places of value. The display only shows whole
increments of counts.
For example, a scale factor of 1.2000 is entered
into the counter. For each pulse received 1.200 is
added to the result. But since the display only indi-
cates whole numbers, after the first pulse it shows
“1”. After 5 pulses it shows “6”. This is shown in
Figure 23.
The scaler stores any remaining partial count and
adds that to the next scaled pulse value when it is
received. This allows accumulation of scaled par-
tial counts.
When a Preset is established on a control with
scaling, the control activates the related output as
shown in Figure 3. But when scaling is used, the
count value is not necessarily a whole number.
The partial count remainder can affect when the
output(s) change state.
With the example of Figure 23, a Preset of 11 is
entered into the control. After the first pulse the
display shows 1 and after the ninth pulse it shows
10. But, the next pulse changes the display to
show 12, bypassing the preset of 11. The counter,
during the process of adding the scaled result to
the total, actually counts from 10 through 11 to 12.
This occurs so swiftly that the value of 11 cannot
be seen on the display. However, the counter does
recognize coincidence at the value of 11 and
changes the state of the output.
As a second example, a Scale Factor of 0.5000 is
entered into the control. Figure 24 gives a table of
pulses received versus displayed value for this
example.
A Preset of 5 is entered when the control is in the
independent output mode. From Figure 24, it is
evident that the output will turn on when the 10th
PULSES
RECEIVED
RESULT
CALCULATED
DISPLAY
VALUE
0
1
2
3
4
5
6
7
8
9
10
0.0000
1.2000
2.4000
3.6000
4.8000
6.0000
7.2000
8.4000
9.6000
10.8000
12.0000
0
1
2
3
4
6
7
8
9
10
12
Figure 23.
Pulses Received versus Dis-
played Value Using Scale Factor of 1.2000
