Types Of Tasks - Omron CJ - PROGRAMMING MANUAL 08-2008 Programming Manual

Task Features
4-1-4

Types of Tasks

Cyclic Tasks
Interrupt Tasks
Power OFF Interrupt Task
Scheduled Interrupt Tasks
I/O Interrupt Tasks
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Tasks are broadly classified as either cyclic tasks or interrupt tasks. Interrupt
tasks are further divided into power OFF, scheduled, I/O (CS Series only), and
external interrupt tasks (CS Series only). Interrupt tasks can also be executed
as extra cyclic tasks.
Note With the CS1-H, CJ1-H, CJ1M, or CS1D Units, interrupt task can be executed
as cyclic tasks by starting them with TKON. These are called "extra cyclic
tasks."
A cyclic task that is READY will be executed once each cycle (from the top of
the program until the END(001) instruction) in numerical order starting at the
task with the lowest number. The maximum number of cyclic tasks is 32.
(Cyclic task numbers: 00 to 31).
If the extra cyclic tasks are used, the CPU Unit supports up to 288 tasks.
An interrupt task will be executed if an interrupt occurs even if a cyclic task
(including extra cyclic tasks) is currently being executed. The interrupt task
will be executed using any time in the cycle, including during user program
execution, I/O refreshing, or peripheral servicing, when the execution condi-
tion for the interrupt is met.
The interrupt tasks can also be used as extra cyclic tasks.
Note The CS1D (for Duplex-CPU Systems), CS1G/H-CPU@@ (-V1), and CJ1@-
CPU@@ CPU Units do not support this function.
The built-in interrupt inputs and high-speed counter inputs on a CJ1M CPU
Unit can be used to activate interrupt tasks. Refer to the CJ Series Built-in I/O
Operation Manual for details.
The power OFF interrupt task will be executed if CPU Unit power is shut OFF.
Only one power OFF interrupt task can be programmed (Interrupt task num-
ber: 1).
Note The power OFF interrupt task must execute before the following time elapses
or the task will be forced to quit.
10 ms – (Power OFF detection delay time)
The power OFF detection delay time is set in the PLC Setup.
A scheduled interrupt task will be executed at a fixed interval based on the
internal timer of the CPU Unit. The maximum number of scheduled interrupt
tasks is 2 (Interrupt task numbers: 2 and 3).
Note The SET INTERRUPT MASK (MSKS(690)) instruction is used to set the inter-
rupt for a scheduled interrupt task. Interrupt times can be set in 10-ms or 1.0-
ms increments in the PLC Setup.
With CJ1-H-R/CJ1M CPU Units, the interrupt times can be set in 0.1-ms
increments.
An I/O interrupt task will be executed if an Interrupt Input Unit input turns ON.
The maximum number of I/O interrupt tasks is 32 (Interrupt task numbers: 100
to 131). The Interrupt Input 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
Section 4-1