Omron SYSMAC CS Series Instruction & Reference Manual page 660

3. Instructions
Precautions in Using Interrupt Tasks
 Precautions for All Interrupts
• When IORF(097), FIORF(225), IORD(222), or IOWR(223) is being executed within an interrupt task
to refresh I/O in a Special I/O Unit, cyclic refreshing with that Special I/O Unit must be disabled in the
PLC Setup.
If cyclic refreshing with the Special I/O Unit is enabled in the PLC Setup and one of the following
operations occurs during an interrupt task, a non-fatal Duplicate Refresh Error will occur and the
Interrupt Task Error Flag (A402.13) will be turned ON.
• I/O refreshing is performed for the same Special I/O Unit by IORF(097) or FIORF(225).
• The same Special I/O Unit's data area is read by IORD(222) or written by IOWR(223).
• When using a CS-series PLC, be sure that the interrupt task does not require more than 10 ms if a
C200H Special I/O Unit is mounted or SYSMAC BUS Remote I/O Slave Rack is connected. If an
interrupt task longer than 10 ms is executed during I/O refreshing with the Special I/O Unit or Slave
Rack, a non-fatal will occur and the Interrupt Task Error Flag (A40213) will be turned ON.
 Precautions for I/O Interrupts
• Only interrupt inputs from CS/CJ-series Interrupt Input Units and C200H Interrupt Input Units are
supported as causes to trigger I/O interrupt tasks. Interrupt inputs from Inner Boards and Special I/O
Units are not supported.
• Interrupt Input Units must be mounted in one of the following slots on the CPU Rack. I/O interrupt
tasks will not be executed if the Interrupt Input Unit is mounted in any other slot.
• CJ2 CPU Units
• CJ2H-CPU6@-EIP: Slots 0 to 3
• CJ2H-CPU6@: Slots 0 to 4
• CJ2M CPU Units: Slots 0 to 4
• CJ1H CPU Units: Slots 0 to 3
• CJ1M CPU Units: Slots 0 to 2
• Words are allocated to Interrupt Input Units in the order that they are mounted from left to right.
• The CS1W-INT01 and the C200HS-INT01 cannot be used at the same time.
• All interrupt inputs that have been detected will be cleared when the interrupt mask is cleared.
• Furthermore, the recorded interrupt cause is not cleared until the corresponding interrupt task has
been completed, so a new interrupt input will be ignored if it is received while the corresponding
interrupt task is being executed.
 Precautions for Scheduled Interrupts
• Be sure that the scheduled interrupt set time interval is longer than the time required to execute the
scheduled interrupt task.
• For scheduled interrupts, MSKS(690) is used only to set the scheduled interrupt interval and does not
set the time to the first scheduled interrupt. To accurately control the time to the first scheduled
interrupt, program CLI(691) to set the time to the first scheduled interrupt just before programming
MSKS(690). If MSKS(690) is used to restart a scheduled interrupt for a CJ1M or CJ2M CPU Unit,
however, the time to the first scheduled interrupt will be accurate even if CLI(691) is not used.
• The time unit for the scheduled interrupt is set in the PLC Setup as the Scheduled Interrupt Interval.
• Scheduled interrupt tasks cannot be used for CJ2H CPU Units if synchronous unit operation is being
used.
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CS/CJ/NSJ Series Instructions Reference Manual (W474)