what is anti passback
To use anti-pass back, you would typically have a reader on both the entrance and the exit sides of the door. Once the cardholder has used his card on the entrance, the card cannot be used again at the entrance until it has been shown to have used the exit. Anti-pass back (APB) is most commonly used in car parks and on turnstiles on construction sites or sites using the access control system as a form of time and attendance. APB is a proven and effective way of managing car park spaces as it prevents a second car access on the same credential.