Rockwell Automation 1772-AF4,D17726.5.3 User Manual, AUX FUNCT PROM - Manual (Page 23)

Programming
Chapter 3
3Ć15
Figure 3.6
General AF4 Subtraction Function Word Digit Format
17 16 15 14 13 12 11 10 7 6 5 4 3 2 1 0
S
Digit 1
(MSD)
Digit 2 Digit 3
Bit No.
Data Address
m
Digit 5
Digit 6
Digit 4
(LSD)
Operand 1
S
Digit 1
(MSD)
Digit 2 Digit 3
Digit 5
Digit 6
Digit 4
(LSD)
Operand 2
S
Digit 1
(MSD)
Digit 2 Digit 3
Result Address
n
Digit 5
Digit 6
Digit 4
(LSD)
Result
D ER E
m + 1
m + 2
m + 3
n + 1
E = Enable Bit (1 = Function in Progress)
S = Sign Bit (1= Negative)
D = Done Bit (1 = Function Complete)
ER = Error Bit (1 = Overflow)
MSD = Most Significant Digit
LSD = Least Significant Digit
11484
3. Enter a data address and a result address.
If we select a data address of 201 and a result address of 305, the AF4
establishes the data table format shown in Figure 3.7. The data address
eventually contains three digits of operand 2. The AF4 reserves the next three
higher addresses for digits 4 through 6 of operand 1 and digits 1 through 6 of
operand 2. The result address contains the most significant three digits of the
result and the next higher address contains the least significant three digits.