What you learn today
- Pressure, air and temperature as a subsystem
- Interface to the centre
The masterpiece week starts with the subsystem everything depends on: life support. It is the first of four sub-chips that control the base together with the central unit at the end of the week. Every sub-chip follows the same interface:
| Memory | Writer | Content |
|---|---|---|
| “LS_Status”, “EN_Status”, “PR_Status”, “LG_Status” | subsystem | 0 fine, 1 warning, 2 fault |
| “LS_Puls”, “EN_Puls”, “PR_Puls”, “LG_Puls” | subsystem | counts up every pass |
| “LS_Auftrag” | central unit | 0 normal, 1 saving mode |
| “EN_Auftrag” | central unit | shedding stage 0 to 2 |
| “EN_Ladung” | power | battery level in percent |
| “PR_Auftrag” | central unit | piece count, 0 = no order |
| “PR_Fortschritt” | production | percent of the order |
| “LG_Bestand”, “LG_Anforderung” | logistics | pieces in storage, desired piece count |
| “Z_Puls” | central unit | heartbeat of the central unit |
Three control loops in one chip
| Loop | Device | Rule |
|---|---|---|
| pressure | active vent “LS_Zuluft” (direction outward into the room) | on below 95 kPa, off above 101 kPa |
| air | filtration “LS_Filter” | on above 1 % CO₂, off below 0.5 % |
| temperature | wall heater “LS_Heizung” | 1 K around the setpoint, normally 21 °C, 18 °C in saving mode |
All three measure at the sensor “LS_Raum”. If it is missing, the emergency mode from week 46 applies: the filter runs all the time, vent and heater are off.
The central unit's order
The central unit may only tell life support one thing: “save energy”. Then the heater's setpoint drops. Nothing more – it switches no vent and no filter, because life support alone is responsible for the breathing air.
lbn tmp SPEICHER HASH("LS_Auftrag") Setting Average
seq tmp tmp 1 # only exactly 1 means saving
select soll tmp T_SPAR T_NORMALEverything except exactly 1 means “normal”, including a missing order memory. If the central unit fails, the base keeps living in normal mode.
Status to the central unit
The status sums up what the central unit needs to know. Warning means: the values are getting out of hand, but the system is still working. Fault means: the chip no longer knows what is going on.
slt status p P_WARN
sgt tmp co2 CO2_WARN
or status status tmp
slt tmp t T_WARN
or status status tmp
select status ok status 2 # without sensor: faultOn top of that the chip counts its heartbeat up in every pass. That is how the central unit recognises that it is alive.
A life support that waits for commands from the central unit is a life support that dies with the central unit. Every control loop here runs without a single value from outside.
Exercise
Task
Build the life support subsystem according to the tables above: heartbeat “LS_Puls”, the three control loops at the sensor “LS_Raum”, saving mode via “LS_Auftrag” and the status in “LS_Status” (1 for pressure below 80 kPa, CO₂ above 2 % or below 15 °C, 2 without sensor).
Hints
Hint 1
Whether the sensor is there shows in a sum: add tmp p co2, add tmp tmp t, snanz ok tmp.
Hint 2
Three hystereses by the same pattern; the filter gets select filter ok filter 1 at the end.
Hint 3
Setpoint: seq tmp order 1, then select soll tmp T_SPAR T_NORMAL, the limits with add/sub and BAND.
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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