786
FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
35 Interrupt Function and Pulse Catch Function
35.3 Input Interrupt (Interrupt Triggered by External Signal) [Without Delay Function]
35.3
Input Interrupt (Interrupt Triggered by External Signal)
[Without Delay Function]
35.3.1
Input interrupt (interrupt triggered by external signal) [without delay function]
1. Outline
An interrupt routine is executed by the input signal from an input X000 to X005.
2. Application
Because the external input signal can be processed without being affected by the operation cycle of the PLC,
this interrupt is suitable to high speed control and receiving of short pulses.
3. Basic program (programming procedure)
Interrupt routine [1]
(interrupt program)
Interrupts are
enabled
FNC 04
EI
FNC 06
FEND
FNC 03
IRET
I001
Interrupt
pointer
When the rising edge of X000 is detected
FNC 03
IRET
Step
0
End of main
program
Main
program
Interrupt return
I100
Interrupt
pointer
When the falling edge of X001 is detected
END
Interrupt routine [2]
(interrupt program)
Interrupt return
Main program
Interrupt inputs are accepted after EI instruction.
It is not necessary to program DI (disable
interrupt) instruction if there is no zone where
input interrupts should be disabled.
FEND instruction finishes the main program.
Make sure to describe an interrupt routine after
FEND instruction.
When X000 turns ON, its rising edge is detected,
and the interrupt routine [1] is executed.
IRET instruction returns the program execution to
the main program.
When X001 turns OFF, its falling edge is detected,
and the interrupt routine [2] is executed.
IRET instruction returns the program execution to
the main program.
"END" indicates the end of program.
