Scada for conveyor belt

The packaging unit of a cement factory is worked in the following way: The packaging is done in sets, each set consists of 10 cement bags. If the number of cement bags is more or less than 10 then the warning arises and the system stops. The standard weight of the cement bags is 50 kg. Tolerance is specified as +-1%. The cement bags with more than 1% margin of error are shifted to the conveyor belt, called as the faulty conveyor belt. The cement bags without any error are loaded onto trucks, by passing through three different conveyor belts. When the ‘Start Loading’ button is pressed, the third conveyor belt starts immediately, whereas the second conveyor belts start 20 seconds after the third belt and the first belt starts 20 seconds after the second belt. If there is a fault in the third conveyor belt, the first and second conveyor belts stop immediately. If there is a fault in the second conveyor belt, the first conveyor belts stop immediately. In case of any fault in the first conveyor belt, only the first belt stops. When the Emergency Stop button is pressed, all the conveyor belts stop.