Mitsubishi Electric MELSEC-Q/L - Recovery from Interrupt Programs

6 BASIC INSTRUCTIONS
6.6 Program Execution Control Instructions
331
6
Recovery from interrupt programs
IRET
Processing details
• Indicates the completion of interrupt program processing.
• Returns to sequence program processing following the execution of the IRET instruction.
Operation error
• In any of the following cases, an operation error occurs, the error flag (SM0) turns ON, and an error code is stored into SD0.
Program example
• The following program adds 1 to D0 if M0 is ON when the number 3 interrupt is generated.
Setting
data
Internal device R, ZR J\ U\G Zn Constant Others
Bit Word Bit Word

Error
code
Error details Q00J/
Q00/
Q01
QnH QnPH QnPRH QnU LCPU
4220 There is no pointer corresponding to the interrupt number. 
4221 After an interrupt occurred, the END, FEND, GOEND, or STOP instruction
was executed prior to the IRET instruction.

4223 The IRET instruction was executed before the interrupt program is executed. 
The IRET instruction was executed during the fixed scan execution type
program.

[Ladder Mode] [List Mode]
Basic
Process
High
performance
Redundant Universal LCPU
IRET
I
IRET
**
Step
Instruction
Device