PLC Program Design Using ST Language-use case structure

program_main:

case (step):

1:

if(condition) then:

action 1;

action 2;

step = 2;

end_if;

2:

if(X0) then:

Y0 := True;

step = 3;

end_if;

3:

if(loop condition) then:

action;

step = 1;

else:

step = 1000; (*no action state*)

end_if;

end case