Decision
The layout starts with track power off
Connecting to the command station checks the power state instead of switching it on. Only an operator turns the track on.
- Status
- accepted
- Decided
- Affects
- Layout Orchestration, PicoDCC
Context
PicoDCC’s tracks come up unpowered. An earlier change (#149) had the orchestrator send “power on” the moment the serial link to the command station connected. The reasoning was that otherwise a cold start would report a healthy link and accept throttle commands into dead rails.
That was the wrong default in service. The link comes up whenever the orchestrator process starts, and every deploy restarts the process. So the layout came to life because somebody pushed a build, with nobody necessarily standing at it. A decoder that loses DCC signal falls back to DC, which on a powered track is full speed.
Decision
On connect, the orchestrator asks the station for its power state and doesn’t set it. The layout comes up dark. Routes and automation are refused until an operator presses On.
What the operator sees is the power state the station reported back, never the state that was requested.
Consequences
- A deploy can’t energise the rails.
- Track power off refuses routes, but isn’t a Safe-Stop and latches nothing. The layout is already stopped, and someone who switched it off to re-rail a wagon shouldn’t come back to a system demanding acknowledgement.
Source: docs/dcc-link.md D14.