Rockwell Automation 1772-LS_LSP,D17726.8.6 PROG/OPER MANUAL-MINI PLC-2/05 - Manual (Page 48)

Chapter
5
5Ć1
Scan Theory
In this chapter you will read about:
scan function
scan time
The processor controls the status of output devices or instructions in accordance
with program logic. Every instruction in your program requires execution time.
These times vary greatly depending upon the instruction, the amount of data to
be operated on, and whether the instruction is true or false.
As a review from chapter 1, there are two types of scans (Figure 5.1):
I/O scan (775
µ
s without forcing: 1 ms with forcing)
Program scan (15ms/K of user memory)
Chapter Objectives
Scan Function