Option A: Problem statement

Q: Develop a ladder logic program for the setup shown below:

Sensors:

$1.$ Water level sensor which is a float switch

$2.$ Water temperature sensor$,$ which is thermistor switch

$3.$ Coffee mass sensor switch

Actuators$/$loads:

IV$,$ OV$,$ DV$,$ CV are all solenoidbased valves which are controlled by corresponding relays.

Heating coil HC also has its own relay. Flow chart for Option A

Start timer

$($T$1)$

$-$ The first steps are similar to HW$6,$ where the water is filled automatically till preset level.

$-$ This is accomplished by opening the inlet valve $($IV$)$ till the water reaches the desired level, which is measured by float sensor $($FS$).$

$-$ Next, the water is heated to a boil using the heater coil $($HC$)$ and measured by thermistor $($Te$).$

$-$ Next, the ground coffee is dispensed using the coffee valve $($CV$),$ till present mass is attained. This is measured by the coffee mass sensor $($MS$).$

$-$ Next, we pour hot water into the strainer using Outlet valve $($OV$)$ and a timer $($T$1).$ For preset time, OV remains open.

$-$ Next, we soak the coffee using timer T$2.$

$-$ Finally, we open and dispense the coffee using a dispense valve $($DV$)$ and a timer T$3.$

Since we use sensor switches, we have an open and closed state, and each state has its corresponding logic. Requirements $($Option A$)$

$-$ You are only required to submit the ladder logic.

$-$ Use the notations $($for example HC$,$ CV$,$ etc..$)$ and sensors given here. Do not make any modifications to the sensors$.$

$-$ You have to use binary logic, therefore, you cannot use any comparators.

$-$ To be fair to the entire class, you cannot use software for implementation or testing. This must be purely your contribution and the logic must be simple binary.

$-$ A key or legend of the sensors and actuators must be placed next to the ladder logic.

$-$ Ladder diagram must have rungs $($horizontal lines$)$ and rails $($vertical lines$).$ You MUST use the template given in class. See lecture video. This includes symbols for switches, coils$/$relays and loads. Failure to use this template means you will be given $0$ points.

Rubric:

$-$ If you have an open logic, you will automatically get $50\backslash \%$ deduction. Open logic means a relay or load that is always being energized.

$-$ If there is no logic, you will get between $10-30\backslash \%$ depending on effort.