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Interrupt Tasks Section 2-3
2-3-3 Application Precautions
Executing IORF(097)
for a Special I/O Unit
If an IORF(097) instruction has to be executed from an interrupt task for a CJ-
series Special I/O Unit, be sure to turn OFF cyclic refresh for the Special I/O
Unit (using the unit number) in the PLC Setup.
A interrupt task error will occur if you try to refresh a Special I/O Unit with an
IORF(097) instruction from an interrupt task while the Unit is also being
refreshed by cyclic I/O refresh or by I/O refresh instructions (IORF(097) or
immediate refresh instructions (!)). If Interrupt Task Error Detection is turned
ON in the PLC Setup when an interrupt task error occurs, A402.13 (Interrupt
Task Error Flag) will turn ON and the unit number of the Special I/O Unit for
which I/O refreshing has been duplicated will be stored in A426 (Interrupt
Task Error, Task Number). The CPU Unit will continue running.
PLC Setup Settings Select or clear the Detect Interrupt Task Error Checkbox in the Execute Pro-
cess Area on the Settings Tab Page in the PLC Setup.
Related Auxiliary Area Flags/Words
Disabling Interrupts With a CP-series CPU Unit, the following processing will be interrupted to exe-
cute an interrupt task.
• Instruction execution
• Refreshing for CPU Unit built-in I/O, CPM1A Expansion Units, CPM1A
Expansion I/O Units, or CJ-series Special I/O Units
• Peripheral servicing
IORF
END
D1
D2
CP1H
Do not executed
IORF(097) in an interrupt
task if cyclic refreshing is
enabled for Special I/O
Units in the PLC Setup.
Disable cyclic refresh-
ing for Special I/O Units
in the PLC Setup before
executing the
IORF(097) instruction in
an interrupt task.
CJ-series Special I/O Unit
I/O refresh
Interrupt task
Incorrect Use Correct Use
Name Setting Description
Detect Interrupt Task
Error
Cleared Interrupt task errors not detected.
Selected Interrupt Task Error Flag (A402.13) turned
ON when an interrupt task error is detected.
Name Address Description
Interrupt Task Error
Flag
A402.13 Turns ON if you try to refresh a CJ-series Special I/O Unit with IORF(097)
from an interrupt task while that Unit is being refreshed by cyclic I/O refresh.
Interrupt Task Error
Unit Number
A426 Bits 00 to
11
The unit number of the Special I/O Unit undergoing duplicate refreshing will
be stored here when A402.13 turns ON.
Interrupt Task Error
Factor Flag
Bit 15 Turns ON to indicate the cause of the error when A402.13 turns ON.
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