Rockwell Automation 1772-LV Mini-PLC - 2/15 Programmable Controller (Series B) Programming and Operations - Manual (Page 60)

Advanced Instruction Set
Chapter 6
6Ć3
NOTE: When your processor is in the test mode, all outputs are not active.
When your processor is in the run mode, all outputs are active.
Scan Time
Scan time is the amount of time it takes the processor to monitor and update
inputs and outputs, and to execute instructions in memory in accordance with
your program. The scan is performed serially; first the I/o image table is
updated, (other parts of the data table are not scanned), then the user program
area is scanned.
There are two ways to measure I/o scan time:
Program the rungs in Figure 6.2. The operations section of this manual
provides general instruction on how to program rungs.
Add the execution values for each instruction by using Table 6.A. The sum
of these values is the I/O scan time.