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Auto: focas-f4c — pmc_wrpmcrng with bit-level RMW

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Closes #270
This commit is contained in:
Joseph Doherty
2026-04-26 05:15:52 -04:00
parent 0c967af645
commit 54c09d4d5d
17 changed files with 837 additions and 101 deletions
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26
docs/Driver.FOCAS.Cli.md
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@@ -120,6 +120,18 @@ otopcua-focas-cli write -h 192.168.1.50 -a MACRO:500 -t Int32 -v 42
otopcua-focas-cli write -h 192.168.1.50 -a PARAM:1815 -t Int32 -v 100
```
> **WARNING — `write -a G50.3 -t Bit -v on` is a read-modify-write.**
> The wire call `pmc_wrpmcrng` is byte-addressed; the driver reads the
> parent byte at `G50` first, sets bit 3, and writes the byte back. Other
> bits in `G50` that the ladder is concurrently updating may be clobbered
> by the byte we read a millisecond ago. Coordinate via a ladder-side
> handshake when this matters. **PMC writes also bypass the ladder's
> normal MDI-mode protection** — a misdirected bit can move motion or
> latch a feedhold the moment it lands. Verify e-stop is live and the
> machine is in JOG mode before issuing the first PMC write of a
> session. See [`docs/drivers/FOCAS.md`](drivers/FOCAS.md) "PMC bit-write
> read-modify-write semantics" for the full RMW flow.
PMC G/R writes land on a running machine — be careful which file you hit.
Parameter writes may require the CNC to be in MDI mode with the
parameter-write switch enabled.
@@ -146,17 +158,17 @@ the operator pre-check runbook (MDI mode, parameter-write switch).
**Writes are non-idempotent by default** — a timeout after the CNC already
applied the write will NOT auto-retry (plan decisions #44 + #45).
#### Server-side `Writes` enforcement (issue #268 F4-a + #269 F4-b)
#### Server-side `Writes` enforcement (issue #268 F4-a + #269 F4-b + #270 F4-c)
The OtOpcUa server gates every FOCAS write behind multiple independent
opt-ins: `FocasDriverOptions.Writes.Enabled` (driver-level master switch),
`Writes.AllowParameter` (PARAM kill switch — F4-b), `Writes.AllowMacro`
(MACRO kill switch — F4-b), and `FocasTagDefinition.Writable` (per-tag).
All default `false`; any one off short-circuits the server-side
`WriteAsync` to `BadNotWritable` before the wire client is touched. See
[`docs/drivers/FOCAS.md`](drivers/FOCAS.md) "Writes (opt-in, off by
default)" subsection + [`docs/v2/decisions.md`](v2/decisions.md) for the
decision record.
(MACRO kill switch — F4-b), `Writes.AllowPmc` (PMC kill switch — F4-c),
and `FocasTagDefinition.Writable` (per-tag). All default `false`; any one
off short-circuits the server-side `WriteAsync` to `BadNotWritable` before
the wire client is touched. See [`docs/drivers/FOCAS.md`](drivers/FOCAS.md)
"Writes (opt-in, off by default)" subsection +
[`docs/v2/decisions.md`](v2/decisions.md) for the decision record.
**The CLI bypasses the server-side flag.** `otopcua-focas-cli write` is a
per-invocation operator tool — it sets `Writes.Enabled = true` locally for