Ok, thank you for the link, but I don't know why the program it's not working on my computer
For short I have to program the C.R. to move a parking barrier, so when a driver push a button(I1) the entrance barrier is going up (Q1), then there I have a "optical barrier"(I2) after the car passes by the barrier goes down(Q1), and the counter goes down whit one ... and so on, after that, when a car leaves the parking area, I have another button(I3) to push to open the exit barrier, and again an "optical barrier" (I4) and the counter goes up whit one....... when the parking area is full I have to make a semafor red (Q3) and when a car (or more) goes....... green ... an so on......