What you learn today
- Check the water supply
- Fill lines
- Report shortage
Hydroponics means the roots hang in water. If the line runs dry, the plant first grows more slowly and takes damage after a while. A chip keeps an eye on the water long before the Harvie's face turns sad.
Where the water is
Hydroponics trays hang on a liquid pipe. The hydroponics device reads the water that is standing in it right now:
| LogicType | means |
|---|---|
Pressure | pressure of the contents |
Temperature | temperature of the water |
RatioWater | share of water in the contents |
TotalMoles | amount of substance of the contents |
For the whole line a liquid pipe analyzer (StructureLiquidPipeAnalyzer) is the right tool. It reads the same values and also VolumeOfLiquid, the volume of the liquid in litres.
Filling lines
The water comes from a liquid tank and flows through a liquid pump (StructureLiquidVolumePump) into the watering line. The chip switches the pump with hysteresis: on when the line pressure drops, off when it is back up. That way there is always water at the trays, but the line is not overfilled.
lbn press ANALYZER HASH("Giessleitung") Pressure Average
slt tmp press P_OFF # below 300 kPa: keep pumping
and pump pump tmp
slt tmp press P_ON # below 150 kPa: start
or pump pump tmp
sbn PUMP HASH("Giessen") On pumpThe numbers are example values. Measure your line when it is well filled and set the limits a little below.
How full is the tank?
The tank itself has no logic any more: its kit builds an in-line tank that belongs to the pipe network. A second liquid pipe analyzer “Wassertank” on the tank line, i.e. before the pump, reports Volume, the capacity of that network in litres, and VolumeOfLiquid, the liquid inside. The quotient is the fill level:
lbn fill ANALYZER HASH("Wassertank") VolumeOfLiquid Average
lbn tmp ANALYZER HASH("Wassertank") Volume Average
div fill fill tmp # 0 to 1Reporting a shortage
Two messages belong here:
- Tank almost empty: fill level below 10 %. Time to melt ice or bring more water.
- Line stays empty: the pump runs, but the pressure does not rise. Then the tank is empty or the line leaks. A counter detects that: it counts up while the pump works and the pressure stays low, and drops to 0 as soon as one of the two is no longer true.
A failed analyzer returns NaN. Then you do not know how full the line is. The hysteresis above switches the pump off by itself on NaN – the shortage light should come on as well so somebody takes a look.
The water counts for the temperature too: according to the game code the plant checks whether its water is in the growth range. A line running outside over the Mars ground cools the roots.
Diagram
Exercise
Task
Build the watering:
- pump “Giessen” on below 150 kPa in the analyzer “Giessleitung”, off above 300 kPa
- display “Tank” shows the fill level at the analyzer “Wassertank” in whole percent, −1 without the analyzer
- light “Wasser” on when the tank is below 10 %, the analyzer is missing or the pump runs for more than 20 ticks without the pressure getting above 150 kPa
Hints
Hint 1
Fill level: VolumeOfLiquid divided by Volume, times 100, rounded. On NaN use select to get −1.
Hint 2
−1 is less than 10 – slt short fill TANK_MIN then reports a missing analyzer by itself.
Hint 3
Counter: add time time tmp and then mul time time tmp – that way it drops to 0 as soon as tmp is 0.
Quiz
4 questions. You pass from 60 % – the server does the grading.
Complete the day
- Passed the simulator exercise
- Passed the quiz with at least 60 %
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