Rockwell Automation 1336E IMPACT Adjustable Frequency AC Drive User Manual V 1-4.XX - Manual (Page 189)

Using the Function Block 10-19
The multiply/divide function can be performed as either standard
math or per unit math. Per unit math lets you multiply/divide internal
drive units on a per unit basis, where 4096 is equal to one unit. With
per unit math, 4096 x 4096 = 4096, because you actually multiply 1
unit by 1 unit to get 1 unit. The equation used for per unit math is as
follows:
In this example, the drive controlling the smaller spindle follows the
speed of the drive controlling the larger spindle. This example is
shown in Figure 10.23.
Figure 10.23
Example of a Drive Ratio
The smaller D2 will spin approximately 4.096 times faster than the
D1 Drive. This Ratio is set by the IN2 and IN3 parameters.
If the current command speed of D1 Speed Ref P29 was 25% of its
base speed, its value would be 1024.
.25 x 4096 (1PU Base Speed) = 1024
IN1 = 1024
IN2 = 16777
IN3 = 4096
Example:
In1 x In2 x 65536
IN3
= 32 bit Out
199 x 8192 x 65536
(IN1)
100 (IN3)
(IN2)
= 1,068,373,115 (decimal)
Output:
1,068,373,115 (dec) =
Whole: Fract:
Hex
MSW LSW
Output: 213
3FAE (hex) = 16,302 (dec)
147B (hex) = 5,243 (dec)
Output: 214
P213
P214
LSW = 0
MSW = 16302
STD Math PU Math
Whl = 16302 dec
Fract = 5243 dec
3FAE 147B
Speed Ref 1
An Out 1 Value
29
105
96 An In 1 Value
Hardwired Connection
Between Drives
D1
D2
198 Func In 1
IN2
IN3
=
16777
4096
=
4.096 PU D2
1 PU D1