CJ2 CPU Unit Software User's Manual - CIP ETI

5 Understanding Programming5-2-3 Interrupt TasksInterrupt tasks can be executed at any time in the cycle if any of the following conditions are in effect.If an interrupt occurs, the interrupt task will be executed at any point in the cycle regardless of whetherthe CPU Unit is currently executing an instruction in a cyclic task, refreshing I/O, or performing peripheralservicing.Types of Interrupt TasksThe following types of interrupt tasks can be used.• Power OFF Interrupt TaskThe power OFF interrupt task will be executed immediately before the power is turned OFF.• Scheduled Interrupt TasksA scheduled interrupt task is used in programs that require scheduling execution of certain parts ofthe user program, such as for monitoring the operation status at constant intervals.• I/O Interrupt TasksAn I/O interrupt task will be executed when an input to an Interrupt Input Unit connected to the CPUUnit turns ON.• External Interrupt TasksAn external interrupt task will be executed when an interrupt is requested by an Special I/O Unit orCPU Bus Unit.• Extra Cyclic TasksExtra cyclic tasks are interrupt tasks treated as cyclic tasks. In this case, the purpose is not interruptprocessing, as is the case for other interrupt tasks, but to increase the number of cyclic tasks. Up to128 cyclic tasks can be used. If extra cyclic tasks are used, however, up to 384 cyclic tasks can beused. List of Interrupt TasksTask Task No. Execution condition Related settingsPower OFF InterruptTask1 Turing OFF the CPU Unit • OFF interrupt tasks for PLC setupScheduled Interrupt 2 and 3 Each lapse of specific time onTasks 0 and 1 *1 internal timer of CPU UnitI/O Interrupt Tasks 0 100 to 131 Input bit from an Interrupt Inputto 31 *2 Unit on the CPU Rack turningONExternal Interrupts 0 0 to 255 When requested by a Specialto 255 *3 I/O Unit or CPU Bus Unit on theCPU Rack *3Extra Cyclic Tasks 0to 2550 to 255 Every cycle while in the task isin READY status. (Task ControlInstructions must be used.)• Use the MSKS(690) (SET INTER-RUPT MASK) instruction to set theinterrupt interval. (1 to 9999)• See Scheduled Interrupt Time Unitsin PLC Setup. (10 ms/1.0 ms/0.1 ms)• Use the MSKS(690) (SET INTER-RUPT MASK) instruction to assigninputs from Interrupt Input Units onthe CPU Rack.None (always valid)None (always valid)*1 The scheduled interrupt tasks cannot be used if synchronous unit operation is being used.*2 The Interrupt Input Unit must be connected in the CPU Rack. I/O Interrupt Units connected elsewhere cannotbe used to request execution of I/O interrupt tasks.*3 The Special I/O Unit or CPU Bus Unit must be connected in the CPU Rack. Units connected elsewhere cannotbe used to generate external interrupts.5-20 CJ2 CPU Unit Software User’s Manual