6. Function blocks6.2 Interrupt function blocks6.2.3 IT - Time-controlled interrupt function blockOnly possible with easySoft 7.6.2.3.1 GeneraleasyE4 base devices provide 8 time-controlled interrupt functionblocks, IT01 through IT08. This does not apply to the EDP pro-gramming language.easyE4 makes it possible to quickly respond to various events. Thismakes it possible, for instance, to switch outputs on or off outside ofthe main program's routine. Only bit operators are allowed within aninterrupt program.Time-controlled interrupt function blocks can be used in on-delayedmode or interval mode.Execution time for an interruptThe time between the moment the event is detected and the momentthere is a response at a device output is < 1 ms. Accordingly, QP -Physical output on base device must be set in the interrupt program.If multiple interrupts are executed simultaneously, the times add up.In total, no more than 8 interrupt sources are allowed tobe processed in a single program. The valid interruptsources are the IC, IE, IT interrupt function blocks andthe CF, CH, and CI high-speed counters that are directlyconnected to the device inputs.If there are multiple interrupt requests present sim-ultaneously, the first detected interrupt program will beexecuted, after which the remaining ones will beexecuted based on the corresponding order.6.2.3.2 Operating principleA reference value is set at function block input PD. As soon as function block input ENis set to 1, the time measurement starts. Depending on the operating mode being used,the system will jump to the interrupt program once or repeatedly as soon as the spe-cified time at function block input PD is reached.Interaction between main program and interrupt programThe states of function block inputs IT_I1 through IC_04 are passed to the interrupt pro-gram, where they can be processed further as I01 through I04.Function block outputs IT_Q1 through IC_Q4 can be set from the interrupt program. Thecorresponding interrupt program outputs are Q01 through Q04.Main program Interrupt program424 easyE4 11/18 MN050009 EN www.eaton.com
