Background Execution - Omron CJ2 - 02-2010 User Manual

10 CPU Unit Functions

10-2-5 Background Execution

Table data processing (such as data searches) and text string processing (such as text string
searches), require time to execute, and can create large fluctuations in the cycle time due to the
extended amount of time required to execute them.
Background execution (time slicing) can be used to execute the following instructions over several
cycles to help control fluctuations in the cycle time. The PLC Setup enables setting background execu-
tion for each type of instruction.
• Table data processing instructions
• Text string processing instructions
• Data shift instructions (ASYNCHRONOUS SHIFT REGISTER only)
Setting background execution for the above instructions can help control temporary increases in the
cycle time.
Without Background
Processing
MAX
Precautions for Correct Use Precautions for Correct Use
Background processing is not performed in interrupt tasks for CJ2H CPU Units when high-speed
interrupts are enabled in the PLC Setup. An instruction processing error will occur.
10-10
With Background
Processing
Long execution time
Longer cycle time when
MAX is executed.

Background execution

Execution
only started.
MAX
CJ2 CPU Unit Software User's Manual
Executed over
several cycles
using time slicing.