CJ2 CPU Unit Software User's Manual - CIP ETI

5 Understanding ProgrammingThere are basically two types of tasks.Type of taskDescriptionApplicable programminglanguageExecution conditionsCyclic tasksExecuted once percycleLadder diagramsSFCSTExecuted when one of the following methods isused to place the task into READY status.• Setting the Activated at the start of operationproperty using the CX-Programmer (programproperty setting)• Turning ON the task by using a Task ControlInstructionInterrupttasks *1,*2Executed when aspecific conditionoccurs. The processbeing executedisinterrupted.Ladder diagramsSTAn interrupt task is placed into READY status whenthe interrupt conditions that is set for it occurs. Conditionscan be set for each of the following interrupttasks.• Power OFF interrupt tasks• Scheduled interrupt tasks• I/O interrupt tasks• External interrupt tasks• Built-in input interrupt tasks (CJ2M CPU Unitsonly)*1 Cyclic execution (i.e., execution once per cycle) can be performed for an interrupt task just as with cyclic tasksby using Task Control Instructions to turn ON the interrupt task. (These tasks are called extra cyclic tasks.)*2 Do not use SFC programs in interrupt tasks. They will not execute normally. SFC programs can be used, however,if the interrupt tasks are executed as extra cyclic tasks.Programs assigned to tasks areallocated in order.Program ACyclictask 1Assignedto a task.ENDInterruptconditionInterrupttaskAssignedto a task.When specified conditions aremet, execution of the other tasksis interrupted and the program inthe interrupt task is executedProgram BENDCyclictask nAssignedto a task.Program CI/O refreshingEND5-12 CJ2 CPU Unit Software User’s Manual