Photoperiod, holds and catch-up

The hub's lights clock, auto photoperiod, sunrise/sunset ramps, the dark-period guard, manual light hold, catch-up and its surprises, the two 4×8 lamps and lamp plugs, and how schedule shifts are confirmed. The Overnight panel on Today reports how the last dark period went for each space: the lowest and highest temperature, humidity and VPD, the peak humidity and the minutes over band. It also says whether the dark held; that needs two observers that agree, and with one it reads unknown.

Each tent's lights-on time and hours are hub numbers. The hub keeps time by SNTP (network time). Settings › System › Time shows the hub clock and drift; CLOCK INVALID means the photoperiod cannot be trusted until it syncs. The clock comes from network time only, and the Pi answers time requests for the kit. While the hub's clock is invalid it holds its last known state: the lamp is left exactly as it is, on or off. It does not invent a catch-up, and it does not switch the lamp off at lights-off, so a lamp that is lit when the clock is lost stays lit through the dark period until the clock is valid again. After a power cut the hub waits up to two minutes for the clock before it resumes.

With Automatic photoperiod on, the hub ramps the SF1000 up over the sunrise minutes at lights-on, holds the target brightness, ramps down over sunset, and keeps the lamp off for at least minimum dark hours. A lamp on during the protected dark period is a critical dark period violation, and the violation stays visible even if the reading later goes stale.

A hold freezes the lamp at its current on/off and brightness and stops the schedule, and any active catch-up, from moving it. It is meant for a few minutes of work under the lamp. The dashboard shows the roll-on a toggle will cause before you confirm, and journals it.

After an outage or a hold, the hub may run catch-up to make up missed lit hours inside the day. Releasing a hold while catch-up is active turns the lamp ON immediately. Cancel catch-up on the Light desk writes off the hours still owed for this cycle only: the lamp returns to the normal window and tomorrow's schedule is unchanged. It does not turn the lamp off by itself while the normal window is open. A hub whose firmware lacks the control shows a note instead of the button; there, keep the hold on until the window ends. Full Auto and the mister have the same release pattern.

The 4×8 tent holds two lamps: one dimmed by the hub and one switched by a smart plug on the hub's clock. Two things to set up:

• In Settings › Devices, bind a smart plug as Lamp plug · 4×8. The brain then switches it with the hub's window. On/off only, and leave an off-only schedule on the plug so a brain outage cannot strand the lamp on. While a Safety cut-off is active the plug is held off, whatever the window says.
• Bind a lux sensor to the tent to at least confirm lit state. The 4×8 Got hours count the lamp plug's reported on-time when the plug has reported since midnight (power at the socket, not a light reading), else the hub-dimmed lamp's history when that output exists, else the schedule window.

Moving a lights-on time, shifting a window or flipping to 12/12 is an explicit action: the brain shows the plan and requires confirm; a shift without confirm is refused. Learning surfaces a suggestion when energy or timing outliers become the norm; it never acts on one growth-priority day.

The SF1000's hardware dimming knob overrides the hub's brightness. The light control path row on the Light desk says what DSC drives and what overrides it.

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DSC-Brain user guide · Photoperiod, holds and catch-up · this page is edited on the site; the Notion original was retired after the mirror