Design: Work-Offset Model (Group 8 + G53/G153/SUPA)

Task: T-043 (architecture/design)

Goal

Define Siemens-compatible architecture for:

• modal Group 8 settable work offsets (G500, G54..G57, G505..G599)
• non-modal suppression controls (G53, G153, SUPA)
• machine-configuration variability for offset availability/ranges

This design maps PRD Section 5.9.

Scope

• Group 8 modal state ownership/propagation
• block-scope suppression context semantics and precedence
• configuration model for machine-dependent offset ranges/aliases
• interaction points with coordinate/frame/dimension state pipeline
• output schema expectations for selected offset and effective suppression

Out of scope:

• full controller frame-chain internals and kinematic transforms
• HMI tooling for zero-offset table editing

Pipeline Boundaries

flowchart LR
  A[G500/G54..G57/G505..G599/G53/G153/SUPA] --> B[Parser + Semantic]
  B --> C[Modal Engine]
  C --> D[AIL Lowering]
  D --> E[AilExecutor]

  P[MachineProfile + WorkOffsetPolicy] --> C
  P --> E

• Parser/semantic:
  • captures modal Group 8 words and suppression commands per block
  • validates supported offset codes against profile range set
• Modal engine:
  • maintains persistent Group 8 selected offset code
  • resolves block-local suppression mask from G53/G153/SUPA
• AIL/executor:
  • carries both selected offset state and effective suppression context
  • exposes runtime-consumable metadata, without embedding full frame math

State Model

Persistent Group 8 modal state:

• g500 (deactivate settable work offset; base-frame behavior by profile)
• g54, g55, g56, g57
• g505..g599 (machine-dependent subset)

Block-scope suppression controls (non-modal):

• G53: suppress settable and programmable work offsets
• G153: G53 suppression plus basic-frame suppression
• SUPA: G153 suppression plus DRF/overlay/external-zero/PRESET suppression

flowchart TD
  S[Current modal Group 8 selection] --> B[Current block]
  B --> X{Has suppression control?}
  X -- no --> E[effective uses modal selection]
  X -- yes --> M[effective suppression mask from G53/G153/SUPA]
  M --> E

Precedence and Scope Rules

1. Group 8 selection is modal and persists across blocks until changed.
2. G53/G153/SUPA are non-modal; they affect only the current block.
3. Suppression controls do not mutate stored Group 8 modal selection.
4. If multiple suppression controls occur in one block, effective mask uses strongest suppression level (SUPA > G153 > G53) and emits a warning.

Applicability examples:

• G54 then motion in next block => G54 remains selected.
• G54 with same-block G53 => selected state remains G54, effective suppression applies for that block only.
• next block without suppression => effective context returns to selected G54.

Configuration / Machine-Profile Model

Required profile fields:

• default_group8_offset (startup selection, e.g. g500 or g54)
• supported_group8_offsets (range set; supports 828D-style variants)
• legacy_aliases (optional mapping such as G58/G59 handling policy)
• duplicate_suppression_policy (warn|error|first_wins)

Validation behavior:

• unsupported Group 8 code emits diagnostic and does not update modal state
• suppression controls always parse; profile may tighten same-block policy

Coordinate Pipeline Integration

Work-offset state composes with other coordinate states:

• dimensions/units (T-042) influence numeric interpretation, not Group 8 ID
• transition/rapid states (T-044/T-045) consume effective coordinate context
• runtime motion/planner uses effective suppression mask plus selected offset identifier to resolve actual frame chain outside parser core

Output Schema Expectations

AIL state instruction concept:

{
  "kind": "work_offset",
  "group8_selected": "g54",
  "suppression": "g53",
  "suppression_scope": "block",
  "source": {"line": 120}
}

Runtime effective context concept:

{
  "effective_work_offset_selected": "g54",
  "effective_work_offset_enabled": false,
  "effective_suppression_mask": "suppress_settable_and_programmable"
}

Notes:

• outputs should include both selected modal code and effective block behavior
• runtime/planner can decide frame-chain math using machine-specific policies

Policy Interface Sketch

struct WorkOffsetPolicy {
  virtual EffectiveWorkOffset resolve(const ModalState& modal,
                                      const BlockContext& block,
                                      const RuntimeContext& ctx,
                                      const MachineProfile& profile) const = 0;
};

Implementation Slices (follow-up)

1. Group 8 modal registry alignment

• ensure full Group 8 code set and profile-backed validation paths

2. Suppression context representation

• add explicit block-level suppression metadata for G53/G153/SUPA

3. AIL/runtime propagation

• expose selected offset + effective suppression metadata per block

4. Diagnostics/policy wiring

• validate unsupported offsets and duplicate suppression controls per policy

Test Matrix (implementation PRs)

• parser tests:
  • Group 8 syntax acceptance/rejection with profile range variants
  • suppression command parse coverage
• modal-engine tests:
  • Group 8 persistence across blocks
  • block-local suppression precedence and non-mutation of modal selection
• AIL/executor tests:
  • selected/effective work-offset metadata stability
  • policy behavior for duplicate suppression words
• docs/spec sync:
  • add work-offset syntax/runtime sections as slices are implemented

Traceability

• PRD: Section 5.9 (settable work offsets + suppression controls)
• Backlog: T-043
• Coupled tasks: T-042 (dimensions), T-044 (transition modes)