interrupt call

how to call interrupt in step7 microwinn ???
and how to return from interrupt to main program ????

Search for the ATCH instruction in MicroWin help. The Interrupt routine automatically returns to the main program after all the code in the interrupt has been executed.

You don't call an interrupt, something causes the interrupt to be called, attached shows a list of possible interrupts plus some more that wouldn't fit on my screen. You create an interrupt by 'insert interrupt' or you use the one that is always created in a blank program. Associate that interrupt routine with an interrupt event as given in the list by using 'Attach interrupt'.
You don't have to tell it to return from an interrupt, it returns when the interrupt has finished running through its code.

Chapter 6, Interrupt Instructions must read!!