LS Industrial Systems SV-iS7 PLC User Manual

Chapter 4 CPU Function
4 - 10
4.3.2 Program Execution Procedure
The following diagram shows that how the CPU module process programs when the CPU
module is powered on or switched to RUN mode.
1) Scan Program
(1) Function
-. The scan program is executed regularly in every scan from 0 step to last step.
-. When interrupts has occurred, CPU pauses scan program and executes corresponding
interrupt program first.
-. When this interrupt program finished, scan program is to resume.
2) Interrupt Program
(1) Function
-. When an interrupt occurs, the CPU module will stop the current operation and execute the
corresponding interrupt routine first. After finish the interrupt routine, the CPU resume the
sequence program from the stopped step.
(2) Type
• PLC Option card provides 2 types of interrupt.
- The TDI (Time driven interrupt) occurs with the constant period
- The PDI (Process driven interrupt) occurs with the status of external input.
Start Processing
Scan Program
End Processing
Subroutine Program
PDI Program
TDI Program
It is executed when
the condition is
satisfied.

LS Industrial Systems SV-iS7 PLC Specifications

General

Brand	LS Industrial Systems
Model	SV-iS7 PLC
Category	Computer Hardware
Language	English