Omron CJ - PROGRAMMING MANUAL 08-2008 Programming Manual page 205

Task Features
External Interrupt Tasks
Note
Extra Cyclic Tasks
Note
one of the three Units next to the CPU Unit (slots 0 to 2). I/O Interrupt Units
mounted elsewhere cannot be used to request execution of I/O interrupt
tasks.
I/O interrupts are not supported by CJ1 CPU Units.
An external interrupt task will be executed when requested by an Special I/O
Unit, CPU Bus Unit, or Inner Board (CS Series only) user program. Special
I/O Units and CPU Bus Units, however, must be mounted to the CPU Rack.
The Special I/O Unit or CPU Bus Unit must be mounted to the CPU Rack. For
CJ1-H CPU Units, the Unit must be connected as one of the five Units next to
the CPU Unit (slots 0 to 4). For CJ1M CPU Units, the Unit must be connected
as one of the three Units next to the CPU Unit (slots 0 to 2). Units mounted
elsewhere cannot be used to generate external interrupts.
The maximum number of external interrupt tasks is 256 (Interrupt task num-
bers: 0 to 255). If an external interrupt task has the same number as a power
OFF, scheduled, or I/O interrupt task, the interrupt task will be executed for
either condition (the two conditions will operate with OR logic) but basically
task numbers should not be duplicated.
I/O interrupts are not supported by CJ1 CPU Units.
1. If another interrupt task is being executed when a scheduled, I/O, or exter-
nal interrupt occurs, then these interrupt tasks will not be executed until the
interrupt task that is currently being executed has been completed. If mul-
tiple interrupts occur simultaneously, then interrupt tasks will be executed
sequentially starting at the lowest interrupt task number.
2. The CJ1 CPU Units do not support I/O interrupt and external interrupt
tasks.
An interrupt tasks can be executed every cycle, just like the normal cyclic
tasks. Extra cyclic tasks (interrupt task numbers 0 to 255) are executed start-
ing at the lowest task number after execution of the normal cyclic task (cyclic
task numbers 0 to 31) has been completed. The maximum number of extra
cyclic tasks is 256 (Interrupt task numbers: 0 to 255). Cycle interrupt tasks,
however, are different from normal cyclic tasks in that they are started with the
TKON(820)instruction.
If an extra cyclic task has the same number as a power OFF, scheduled, or I/O
interrupt task, the interrupt task will be executed for either condition (the two
conditions will operate with OR logic). Do not use interrupt tasks both as nor-
mal interrupt tasks and as extra cyclic tasks.
1. TKON(820) and TKOF(821) can be input and executed in an extra cyclic
task, but they will not be executed when the task operates as an interrupt
task.
2. The differences between normal cyclic tasks and extra cyclic tasks are list-
ed in the following table.
Item
Activating at startup
Task Flags
Initial Task Execution
Flag (A20015) and
Task Start Flag
(A20014)
Extra cyclic tasks
Setting is not possible.
Not supported.
Not supported.
Section 4-1
Normal cyclic tasks
Set from CX-Programmer
Supported. (Cyclic task
numbers 00 to 31 corre-
spond to Task Flags TK00 to
TK31.)
Supported.
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