Instrument modes#

A mode is a named operating context. It determines which daemons must be ready, which limits apply, which commands are permitted, and which interlocks are active.

Modes are configuration, not code.

Mode	Purpose	Characteristics
`science`	Nominal observing	Observing limits. The sequencer drives. Lamps interlocked off. All daemons required for the selected channels must be `ready`.
`acquisition`	Target acquisition and centring	Observing limits. Telescope offsets permitted. Short exposures. Transitions to `science` on acquisition.
`calibration`	Arcs, flats, darks	Front-end selector in a calibration position. Lamps permitted. Telescope motion not required. Runs during the day as well as at night.
`engineering`	Hard hat operation	Engineering limits. Direct device addressing. Announced to observers. Refused while a sequence is running.
`maintenance`	Servicing, warm-up, pump-down	Motion may be inhibited entirely. Thermal and vacuum operations permitted that no other mode allows. Detector power-down permitted.
`safe`	Commanded safe state	All daemons in their safe states. Only `recover` and reads accepted.

Selecting a mode#

Mode is instrument-wide and held by zsseq_obs, with two qualifications:

engineering is held per subsystem. One arm can be under engineering control while the rest of the instrument remains in science: but the observer GUI announces it, and the sequencer will not include that subsystem in a science sequence.
safe is reachable from any mode and is never refused.

Transitions#

        stateDiagram-v2
    [*] --> safe: boot
    safe --> calibration: recover + configure
    safe --> acquisition
    calibration --> acquisition
    acquisition --> science: target acquired
    science --> acquisition: next target
    science --> calibration: calibration set
    acquisition --> engineering: sequence stopped
    calibration --> engineering
    science --> engineering: sequence stopped
    engineering --> calibration: exit hard hat
    engineering --> maintenance
    maintenance --> engineering
    science --> safe: fault / commanded
    acquisition --> safe
    calibration --> safe
    engineering --> safe
    maintenance --> safe

Entering engineering from science requires the running sequence to be stopped first; the sequencer does not silently yield the instrument.

Leaving engineering does not return the instrument to ready. Readiness is re-established and re-observed, because the mechanism state after an engineering session is not assumed.

Required daemons per mode#

Each mode declares in configuration which daemons must be ready. This is what allows partial operation: a NIR spectrograph that is warm does not prevent a VIS-only programme, and neither prevents imaging.

Mode	Required
`science`	`zsseq_obs`, `zskeck_tcs`, `zsfe_selector`, and the motion and detector daemons of every selected assembly, plus `zshouse_cryo`, `zshouse_thermal`, and `zshouse_vacuum` when the NIR spectrograph is in use.
`acquisition`	As `science`, plus `zskeck_acq`. Acquisition itself is performed by MAGIQ, which ZShooter waits on rather than drives.
`calibration`	`zsseq_obs`, `zsfe_cal`, `zsfe_selector`, and the motion and detector daemons of every selected assembly. Not `zskeck_tcs`.
`engineering`	Only the daemons being worked on.
`maintenance`	`zshouse_vacuum`, `zshouse_thermal`, `zshouse_cryo`, `zshouse_glycol`, and `zshouse_power`.

Note

TBC: observing modes

The instrument’s scientific observing modes (which channel combinations, slit widths, and readout modes are supported, and which are simultaneous) come from the L1/L2 requirements and are not yet captured here. They will determine the observing-configuration vocabulary the observer GUI presents and the required-daemon sets above.