Recovery From Interrupt Programs - Mitsubishi MELSEC-Q/L Programming Manual

IRET
6.6.2 IRET

Recovery from interrupt programs

6.6.2
IRET
IRET
Internal Devices
Setting
Data
Bit Word
––
Function
(1) Indicates the completion of interrupt program processing.
(2) Returns to sequence program processing following the execution of the IRET instruction.
Operation Error
(1) In any of the following cases, an operation error occurs, the error flag (SM0) turns ON, and an error code is stored into
SD0.
Error
code
4220 There is no pointer corresponding to the interrupt number.
After an interrupt occurred, the END, FEND, GOEND, or STOP
4221
instruction was executed prior to the IRET instruction.
The IRET instruction was executed before the interrupt program is
4223
executed.
The IRET instruction was executed during the fixed scan execution type
4223
program.
Program Example
(1) The following program adds 1 to D0 if M0 is ON when the number 3 interrupt is generated.
[Ladder Mode]
284
**
I
J \
R, ZR
Bit
Error details
[List Mode]
Step
High
Basic
performance
U \G
Word
––
Q00J/
Q00/ QnH
Q01
–– ––
Instruction Device
Process LCPU
Redundant Universal
IRET
Zn Constants Other
QnPH QnPRH QnU LCPU
–– ––