204
FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
8 Program Flow – FNC 00 to FNC 09
8.4 FNC 03 – IRET / Interrupt Return
8.4
FNC 03 – IRET / Interrupt Return
Outline
This instruction returns the program execution from an interrupt routine to the main program.
1. Instruction format
2. Set data
3. Applicable devices
Explanation of function and operation
When an interrupt (input, timer or counter) is generated while the main program is executed, the program
execution jumps to an interrupt (I) routine.
IRET instruction returns the program execution to the main routine.
The table below shows three types of jump to an interrupt routine.
1. Types of interrupt function
→
For the interrupt function, refer to Chapter 35.
Operand type
Description
Data type
–
There is no set data.
–
Oper-
and
Type
Bit Devices
Word Devices
Others
System User
Digit Specification
System User
Special
Unit
Index
Con-
stant
Real
Number
Charac-
ter String
Pointer
X Y M T C S D
.b KnX KnY KnM KnS
T
C
D
R U
\G
V
Z Modify K
H
E
"
"
P
–
There are no applicable devices.
Function
Interrupt No.
Description
Reference
Input interrupt
I00* to I50*
Executes the interrupt processing when an input (X) signal turns
ON or OFF.
Section 35.3
and
Section 35.4
Timer interrupt
I6** to I8**
Executes the interrupt processing at a specified time interval
(constant cycle).
Section 35.5
Counter interrupt
I010 to I060
Executes the interrupt processing when a high speed counter
reaches counting up.
Section 35.6
FNC 03
IRET
IRET
Mnemonic
Operation Condition
Continuous
Operation
Independent Inst.
1 step
This instruction is the independent type, and
does not require drive contact.