Rockwell Automation 1772-AF1,D17726.5.1 User Manual MINI-PLC-2/15 - Manual (Page 21)

Programming
Chapter 3
3Ć13
4. Enter values for operands 1 and 2.
You can enter these values from the keyboard of your industrial terminal or
through ladder diagram functions. Entry of operand 1 = 102746 and operand 2
- 256384 produces the result -153638 when the subtraction function executes.
Figure 3.8 shows how the result is stored.
Figure 3.8
AF1 Subtraction Function Format After Execution
17 16 15 14 13 12 11 10 7 6 5 4 3 2 1 0
S
0 2
Bit No
Data Address
Operand 1
Operand 2
S
Result Address
Result
D ER E
E = Enable Bit (1 = Function in Progress)
S = Sign Bit (1= Negative)
D = Done Bit (1 = Function Complete)
ER = Error Bit (1 = Overflow)
11486
201
202
203
204
305
306
(0)
S
(0)
1
4 6 7
5 6 2
8 4 3
5 3 1
3 8 6
(0) (1) (1) (0)
Entry and Display of Input and Result Values
Figure 3.9 shows one method for inserting input values and displaying input
values and results of AF1 subtraction computations. Although there are several
techniques for accomplishing this, we chose get instructions. The first rung
requests an AF1 subtraction. The second rung shows the two operands in its top
branch and the resultant difference in its lower branch.