What you learn today
- Take CO₂ out of the air
- Switch by gas ratio
- Report empty filters
Every breath brings CO₂ into the living quarters. In the game it is not poisonous, but it pushes the pressure up and over time crowds out the rest of the air. And for the greenhouse it is worth its weight in gold. So you take it out – but only when needed.
Switching by gas share
The gas sensor delivers RatioCarbonDioxide as a share from 0 to 1. So 1 % is 0.01. With a single threshold the filter would keep switching on and off as soon as the share hovers around the value. Hence two thresholds, the familiar hysteresis pattern:
sgt tmp co2 OFF_AT # still above the lower limit?
and active active tmp
sgt tmp co2 ON_AT # already above the upper limit?
or active active tmpactive then goes to On and to Mode of the filtration unit.
The safe direction
If the sensor fails, Average returns NaN. What is safe then? A heating controller switches off, a generator on. For a CO₂ scrubber, keep filtering is the safe direction: taking CO₂ out never hurts, and the filter only wears when it really catches CO₂.
seqz tmp ok # no reading?
or active active tmp # ... then filterReporting empty filters
lbns reads the quantity of both filters. If one is at 0 or there is no filter in the slot at all, the warning light goes on. If the sensor is missing, too – someone has to check.
Do not confuse the share with percent. sgt tmp co2 1 compares with 100 % and never switches. Either define the threshold as 0.01 or multiply the reading by 100 first – but not both.
A tank for the filtered CO₂ belongs behind the unit. If it fills up, the back pressure rises and the unit manages less and less. An analyzer on the tank tells you in time.
Diagram
Exercise
Task
The sensor “Wohnraum” measures the CO₂ share, the filtration unit “CO2Filter” has two CO₂ filters.
- Filter (On and Mode = 1) from above 1 % CO₂, stop only below 0.5 %
- Sensor gone: keep filtering
- Flashing light “Filterwechsel” on when a filter is at 0 or the sensor is missing
- Display “CO2” shows the share in percent, −1 without sensor
Hints
Hint 1
Hysteresis: sgt/and with OFF_AT, then sgt/or with ON_AT.
Hint 2
On without a reading: seqz tmp ok and or active active tmp – before writing to the unit.
Hint 3
Filters: read both with lbns, min, then slez warn tmp.
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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