Omron SCARA YRCX Series, Руководство по программированию, Страница: 67 / 506

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Outline 6-1
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Outline
The multi-task function performs multiple processing simultaneously in a parallel manner, and can
be used to create programs of higher complexity. Before using the multi-task function, read this
section thoroughly and make sure that you fully understand its contents.
Multi-tasking allows executing two or more tasks in parallel. However, this does not mean that
multiple tasks are executed simultaneously because the controller has only one CPU to execute the
tasks. In multi-tasking, the CPU time is shared among multiple tasks by assigning a priority to each
task so that they can be executed efficiently.
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A maximum of 16 tasks (task 1 to task 16) can be executed in one program.
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Tasks can be prioritized and executed in their priority order (higher priority tasks are executed first).
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The priority level can be set to any level between 1 and 64.
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Smaller values have higher priority, and larger values have lower priority
(High priority: 1
⇔
64: low priority).
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Task definition method
A task is a set of instructions which are executed as a single sequence. As explained below, a task is
defined by assigning a label to it.
1. Create one program that describes a command which is to be defined as a task.
2. In the START statement of the program that will be a main task, specify the program created at
Step 1 above. Task numbers are then assigned, and the program starts.
SAMPLE
’MAIN TASK(TASK1)
START <SUB_PGM>,T2 ················· <SUB_PGM> is started as Task 2
*ST1:
MOVE P,P1,P0
IF DO(20)= 1 THEN
HALTALL
ENDIF
GOTO *ST
HALTALL
Program name:SUB_PGM
’SUB TASK(TASK2)
*IOTASK:
························ Task 2 begins here
IF DI(21)=1 THEN
DO(30)=1
ELSE
DO(30)=0
ENDIF
GOTO *IOTASK ······················· Task 2 processing ends here
EXIT TASK