m.rahmy

i have a question about SFC , if the step is active then processor execute code inside this step and writes on outputs true or false , then when the step deactivated the processor won't execute the code inside the step and won't write true or false on outputs. this means if output Y1 becomes true in activated step then it will remain true after deactivation , right ? in this picture if S41 is active , then M77 becomes true , then S43 becomes active , and S41 isn't active , then M77 will remain true and the processor won't execute S41 , or will becomes false then processor stops executing S41 .

i want to know the role of M2 is to enable the comparison function or it's anded  with the output of the function. in another words if M2 is true and the output of the function is true then M3 is true, but what if M2  becoms false if it's anded with the output of the function then M3 is false , but if M2 stops the execution of the function M3 will remain true, so i need to know if it controllers the execution or it's just anded.