Related Items - Mitsubishi Electric MELSEC FX3U Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
2. Disabling interrupt pointers (for each interrupt routine) [interrupt function]
1) Programming method
The special auxiliary relays M8050 to M8059 for disabling interrupt are provided.
While an interrupt disable flag (M8050 to M8059) is ON, a corresponding interrupt program is not
executed even if the interrupt disable flag is set to OFF after a corresponding interrupt is generated.
Input interrupt
Timer interrupt
High speed counter
interrupt
*1. Cleared when the PLC mode is changed from RUN to STOP.
2) Program example
In the program example shown below, when M8053 is set to ON by M20, the interrupt input I301 triggered
by X003 is disabled.
Interrupt
pointer
I301

36.2.2 Related items

1. Using the I/O refresh function (REF instruction)
When controlling an input relay or output relay in an interrupt program, the I/O refresh instruction REF (FNC
50) can be used to acquire the latest input information and immediately output the operation result. As a
result, high speed control is achieved without being affected by the operation cycle of the PLC.
2. Interrupt operation while FROM/TO instruction is executed
The interrupt operation is executed as follows depending on the ON/OFF status of the special auxiliary relay
M8028.
1) While M8028 is OFF
While FROM/TO instructions are being executed, interrupts are automatically disabled. Input interrupts
and timer interrupts are not executed.
Interrupts generated during this period are immediately executed when the execution of FROM/TO
instructions are completed.
FROM/TO instruction can be used in an interrupt program when M8028 is OFF.
2) While M8028 is ON
When an interrupt is generated while a FROM/TO instruction is being executed, execution of the FROM/
TO instruction is paused and the interrupt is immediately executed.
FROM/TO instructions cannot be used in an interrupt routine program when M8028 is ON.
852
The input interrupts X000 to X005 correspond to M8050 to M8055
M8050 to M8055 turns ON, a corresponding input interrupt is disabled.
The timer interrupts I6
relay M8056 to M8058 turns ON, a corresponding timer interrupt is disabled.
*1
When M8059 turns ON, all of the high speed counter interrupts I010 to I060 are disabled.
FNC 04
EI
M20
M8053
Command to disable
an interrupt triggered
by X003
FNC 06
FEND
When the rising edge of X003 is detected
FNC 03
IRET
END
36 Interrupt Function and Pulse Catch Function
to I8 correspond to M8056 to M8058
Interrupts are
enabled
Interrupt
routine
36.2 Common Items
*1
respectively. When a relay
*1
respectively. When a