Automatic parking system

Hi guys, am working on a small automatic parking system where photocell controlling the actuation of cylinder that is opening and closing the gate. My problem is i want a situation whereby when i have many cars to come in the memory marker to set the opening and closing of the gate will remain latched and the counter will count until the last car has passed. before it rest and the gate closes. Please does anyone has a better idea? Thanks

OK, let me get this straight... A car pulls up, the photocell detects it, and the gate opens. In other words, every car is allowed into the car park.

Just remove the gate and let the photocell count the cars... Problem solved!...

Now, assuming you really want to keep this pointless gate...

I'm not sure I understand how it operates. Does the gate currently go down after every car, but you want it to stay up when there are multiple cars in a row, or vice versa?



-Eric

Oh wait... Might this be a homework question?

The best option is to use two photcells with a distance so that only one photocel detects only one car and two photcells gets detected only when one is behind the other. Everytime when two photcells are detected latched the gate. You can reset the latched memory when both phocells do not detects with a on delay timer so that the last car also has enough time to pass the gate and to avoid any confusion if both photocells happens not to detect in between cars.
If only front photocells detects then you can use the same thing now you use and use logic "OR" condition for the gate to operate so that the gate will work for both situation when there is only one car and many cars