A particular vehicle’s three step DPS gearbox is driven by two hydraulic valves which are controlled by two solenoids. The gear is selected using two push buttons: one for gear up (DPS+), one for gear down (DPS-). Pushing the button one time steps gear one step up or down.
Sequential logic shall fulfill the following requirements:
1. After the solenoid(s) state(s) has changed there shall be 100 ms (±5 ms) delay. 100 ms is typical action delay of the magnetic valve that controls the hydraulics.
2. Only one solenoid may be driven at time and every time the state of the solenoid changes, there must be a 100 ms delay before any further action.
3. After POR (power on reset) there shall be a 500 ms delay before solenoids and indicator lamps are driven. As presented in state diagram gear I is selected after power is switched on.