Acroloc-Centroid

Centroid CNC12 PLC program and M-code macros for an Acroloc mill retrofitted with a Centroid ALLIN1DC motion controller (MPU11-based).

This repo is the controller-level source: a PLC program written in Centroid's stage/ladder language, plus the M-function macros that the CNC calls. It is compiled and loaded by the Centroid CNC12 software (cncm) on the Windows control PC — there is no build step in this repository.

Custom logic added for this machine is tagged with the comment marker ; Acroloc throughout the .src.

A full line-referenced specification of the PLC program lives in docs/plc-spec/, split into one file per subsystem. Start with the scan model and the definitions atlas — every other file cites them instead of repeating naming/timing rules.

• docs/plc-spec/scan-model.md — how the .src actually executes each scan: stage sweep order, same-scan-vs-next-scan SET/RST timing, timer semantics, and write-conflict resolution. Read this first.
• docs/plc-spec/definitions.md — the resource atlas: every symbol in the definitions block (_I/_O/_M/_W/_T/_SV/_C/stage) mapped to its source line, plus the message-constant encoding rule.
• docs/plc-spec/boot.md — what happens before the machine is ready to run: WatchDogStage, InitialStage's one-scan power-up latch (including the Acroloc power-up gear defaults), and the LoadParametersStage parameter-load handshake.
• docs/plc-spec/main-stage.md — MainStage (STG4): E-stop/ reset, probe protection, fault aggregation, M-code housekeeping, the ATC kickoff/safety rungs, and the spindle/coolant/gear-decision logic structurally nested under it.
• docs/plc-spec/atc.md — the custom Acroloc automatic tool changer: mfunc6.mac's macro orchestration, the MainStage kickoff/safety rungs, and the ATCStage (STG16) carousel-indexing state machine, including the base-16-as-decimal position-switch encoding and the 20 s carousel-search watchdog.
• docs/plc-spec/gear-shift.md — the custom RPM-based automatic two-speed clutch selection: the DesiredRange_W decision logic, the mutual-exclusion clutch interlock, and the GearShiftStage (STG17) open-loop neutral-coast-engage sequence.
• docs/plc-spec/jog-and-mpg.md — the operator jog/MPG path: hardwired MPG, wireless/USB MPG, jog-panel key decode/override math, and the four configuration-selected axis-mapping stages.
• docs/plc-spec/faults-and-messages.md — drive/ fiber/PLC-bus/MiniPLC communication-health checks and the fault-bit -> message-word -> on-screen operator message pipeline.
• docs/plc-spec/parameters.md — every SV_MACHINE_PARAMETER_n the .src reads, in one table, each row citing the reading rung and the subsystem file that documents it.

The Acroloc spindle has a two-speed transmission (low / high range). The current gear is tracked from the clutch outputs the PLC itself commands (not a sense switch), and the PLC automatically shifts range based on the commanded spindle RPM — an open-loop, timed neutral-coast-then-engage clutch swap with no rev-match or position feedback. Power-up leaves the transmission in neutral (both clutches energized — both off would be a mechanical lockup); the gear is unknown until the first spin-up engages one. Full line-referenced detail (decision logic, DAC-ratio math, clutch interlock, the GearShiftStage state machine, and the P860–P863 parameter table) is in docs/plc-spec/gear-shift.md; on-machine verification steps (shift boundaries, coast-dwell tuning, RPM accuracy) are in docs/testing/rpm-gear-shift-test-plan.md.

The Acroloc uses a rotary carousel tool changer. It is a Z-motion mechanical changer, not a modern arm type: at machine Z0 the spindle is empty (the tool rests in the carousel), the tool locks to the spindle at about Z -1.5", and the spindle may spin by about Z -1.75/-2". A tool change spans three places: mfunc6.mac (the M6 macro), the ATC kickoff/safety logic in MainStage, and the ATCStage (STG16) state machine that decodes the 5 carousel position switches (a bin/position ID, base-16 encoded as decimal) and indexes to the requested tool's bin. A 20 s watchdog faults the search if the bin is never found. All of this is custom work tagged ; Acroloc.

Tool-to-bin mapping. Tool numbers are decoupled from bins, so a tool numbered above the 12 physical bins can be used. The map lives in CNC12's Tool Library Bin column (non-random enhanced ATC, P160 = 1): M107 sends the requested tool's bin to the PLC, which range-guards it and indexes the carousel, and reports its settled position back so CNC12 can keep the library's bin fields current. See docs/superpowers/specs/2026-09-06-enhanced-atc-nonrandom-design.md and the on-machine procedure in docs/testing/enhanced-atc-nonrandom-test.md.

Full line-referenced detail — the three-piece flow, the I/O table, the carousel position encoding, and manual unlock — is in docs/plc-spec/atc.md (pinned to an older commit; see its banner) and, for the current flow, the acroloc-s10 skill's reference/atc-flow.md.

The on-screen operator panel is a generated retro theme: edit tools/vcpgen.py and re-run it — never hand-edit the emitted resources/vcp/ files (python3 tools/test_vcpgen.py checks the output).

Several CNC12 files on the control PC are customized for this machine and tracked here (language.msg parameter labels, plcmsg.txt operator messages, cncm.hom homing). A CNC12 upgrade can overwrite them — see docs/control-pc-customizations.md for what is customized and how to restore it.