docs(phase4b): Modbus driver-type canonical + Galaxy nesting + FOCAS auto-scale (managed-backend caveat)

2026-06-16 19:58:11 -04:00
parent 6855be288f
commit 08a6551360
4 changed files with 17 additions and 7 deletions
@@ -164,9 +164,11 @@ before publishing, so a CNC that reports millimetres × 1000 is corrected by set
 ]
 ```

-Auto-fetching the decimal-place count via `cnc_getfigure` is deferred (wire-gated). Until
-that lands, the config field is the authoritative source — consult the MTB / machine
-parameter sheets for the correct value. Negative values are clamped to `0`.
+The driver now attempts to auto-scale each axis position using the CNC's `cnc_getfigure` figure when available; `PositionDecimalPlaces` is the **per-axis fallback** used only when the CNC reports no figure for that axis. **Caveat:** the managed `WireFocasClient` (FOCAS/2 Ethernet wire protocol) does not issue `cnc_getfigure` today, so on real hardware all axes still fall back to the manual `PositionDecimalPlaces` config field. Live auto-fetch is a follow-up requiring a `cnc_getfigure` command in `FocasWireClient`. Negative values from `PositionDecimalPlaces` are clamped to `0`.
+
+**Follow-ups (known gaps, non-blocking):**
+- No upper-bound clamp on the figure magnitude returned by the CNC — a misbehaving figure could overflow `Math.Pow`; a max-figure guard should be added.
+- The negative-figure branch (falls back to manual `PositionDecimalPlaces`) is handled but not explicitly unit-tested.

 **Still user-authored**: `PARAM:6711`, `MACRO:500`, `R100` etc. — specific
 numbers whose meaning is MTB-specific. Those go under the device folder