Rockwell Automation 1772-AF4,D17726.5.3 User Manual, AUX FUNCT PROM - Manual (Page 42)

Programming
Chapter 3
3Ć34
4. Enter the operand.
You can enter the operand from the keyboard of your industrial terminal or
through ladder diagram functions. Entry of operand - 648 produces the result
2.81157 when the log function executes. Figure 3.29 shows how the result is
stored.
Figure 3.29
AF4 Log to Base 10 Function Format After Execution
17 16 15 14 13 12 11 10 7 6 5 4 3 2 1 0 Bit No.
Data Address Operand
Result Address
D E
E = Enable Bit (1 = Function in Progress)
ER = Error Bit (1 = Input is 0) 11507
D = Done Bit (1 = Function Complete)
Result
201
305
306
(0) (1)
6 4 8
2 8 1
1 5 7
ER
(0)
Entry and Display of Input and Result Values
Figure 3.30 shows one method for inserting the operand and displaying the
input value and result of an AF4 log to base 10 function. Although there are
several techniques for accomplishing this, we chose get instructions. The first
rung requests an AF4 log to base 10 function. The second rung shows the
operand 648 in word 201 in the upper branch and the desired log 2.81157 in
words 305 and 306 in the lower branch.
Figure 3.30
AF4 Log to Base 10 Function Input and Result Display Rungs
201
648
G
305
281
G
306
157
G
Bit
Storage
Execute Aux
Function
Function Number:
Data Addr:
Result Addr: 30
201
305