Files
Joseph Doherty
8d88ffa14d
FOCAS Tier-C PR E — ops glue: ProcessHostLauncher + post-mortem MMF + NSSM install scripts + doc close-out. Final of the 5 PRs for #220. With this landing, the Tier-C architecture is fully shipped; the only remaining FOCAS work is the hardware-dependent FwlibHostedBackend (real Fwlib32.dll P/Invoke, gated on #222 lab rig).
Production IHostProcessLauncher (ProcessHostLauncher.cs): Process.Start spawns OtOpcUa.Driver.FOCAS.Host.exe with OTOPCUA_FOCAS_PIPE / OTOPCUA_ALLOWED_SID / OTOPCUA_FOCAS_SECRET / OTOPCUA_FOCAS_BACKEND in the environment (supervisor-owned, never disk), polls FocasIpcClient.ConnectAsync at 250ms cadence until the pipe is up or the Host exits or the ConnectTimeout deadline passes, then wraps the connected client in an IpcFocasClient. TerminateAsync kills the entire process tree + disposes the IPC stream. ProcessHostLauncherOptions carries HostExePath + PipeName + AllowedSid plus optional SharedSecret (auto-generated from a GUID when omitted so install scripts don't have to), Arguments, Backend (fwlib32/fake/unconfigured default-unconfigured), ConnectTimeout (15s), and Series for CNC pre-flight. Post-mortem MMF (Host/Stability/PostMortemMmf.cs + Proxy/Supervisor/PostMortemReader.cs): ring-buffer of the last ~1000 IPC operations written by the Host into a memory-mapped file. On a Host crash the supervisor reads the MMF — which survives process death — to see what was in flight. File format: 16-byte header [magic 'OFPC' (0x4F465043) | version | capacity | writeIndex] + N × 256-byte entries [8-byte UTC unix ms | 8-byte opKind | 240-byte UTF-8 message + null terminator]. Magic distinguishes FOCAS MMFs from the Galaxy MMFs that ship the same format shape. Writer is single-producer (Host) with a lock_writeGate; reader is multi-consumer (Proxy + any diagnostic tool) using a separate MemoryMappedFile handle. NSSM install wrappers (scripts/install/Install-FocasHost.ps1 + Uninstall-FocasHost.ps1): idempotent service registration for OtOpcUaFocasHost. Resolves SID from the ServiceAccount, generates a fresh shared secret per install if not supplied, stages OTOPCUA_FOCAS_PIPE/SID/SECRET/BACKEND in AppEnvironmentExtra so they never hit disk, rotates 10MB stdout/stderr logs under %ProgramData%\OtOpcUa, DependOnService=OtOpcUa so startup order is deterministic. Backend selector defaults to unconfigured so a fresh install doesn't accidentally load a half-configured Fwlib32.dll on first start. Tests (7 new, 2 files): PostMortemMmfTests.cs in FOCAS.Host.Tests — round-trip write+read preserves order + content, ring-buffer wraps at capacity (writes 10 entries to a 3-slot buffer, asserts only op-7/8/9 survive in FIFO order), message truncation at the 240-byte cap is null-terminated + non-overflowing, reopening an existing file preserves entries. PostMortemReaderCompatibilityTests.cs in FOCAS.Tests — hand-writes a file in the exact host format (magic/entry layout) + asserts the Proxy reader decodes with correct ring-walk ordering when writeIndex != 0, empty-return on missing file + magic mismatch. Keeps the two codebases in format-lockstep without the net10 test project referencing the net48 Host assembly. Docs updated: docs/v2/implementation/focas-isolation-plan.md promoted from DRAFT to PRs A-E shipped status with per-PR citations + post-ship test counts (189 + 24 + 13 = 226 FOCAS-family tests green). docs/drivers/FOCAS-Test-Fixture.md §5 updated from "architecture scoped but not implemented" to listing the shipped components with the FwlibHostedBackend gap explicitly labeled as hardware-gated. Install-FocasHost.ps1 documents the OTOPCUA_FOCAS_BACKEND selector + points at docs/v2/focas-deployment.md for Fwlib32.dll licensing. What ISN'T in this PR: (1) the real FwlibHostedBackend implementing IFocasBackend with the P/Invoke — requires either a CNC on the bench or a licensed FANUC developer kit to validate, tracked under #220 as a single follow-up task; (2) Admin /hosts surface integration for FOCAS runtime status — Galaxy Tier-C already has the shape, FOCAS can slot in when someone wires ObservedCrashes/StickyAlertActive/BackoffAttempt to the FleetStatusHub; (3) a full integration test that actually spawns a real FOCAS Host process — ProcessHostLauncher is tested via its contract + the MMF is tested via round-trip, but no test spins up the real exe (the Galaxy Tier-C tests do this, but the FOCAS equivalent adds no new coverage over what's already in place). Total FOCAS-family tests green after this PR: 189 driver + 24 Shared + 13 Host = 226. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
FOCAS Tier-C PR C — IPC path end-to-end: Proxy IpcFocasClient + Host FwlibFrameHandler + IFocasBackend abstraction. Third of 5 PRs for #220. Ships the wire path from IFocasClient calls in the .NET 10 driver, over a named-pipe (or in-memory stream) to the .NET 4.8 Host's FwlibFrameHandler, dispatched to an IFocasBackend. Keeps the existing IFocasClient DI seam intact so existing unit tests are unaffected (172/172 still pass). Proxy side adds Ipc/FocasIpcClient (owns one pipe stream + call gate so concurrent callers don't interleave frames, supports both real NamedPipeClientStream and arbitrary Stream for in-memory test loopback) and Ipc/IpcFocasClient (implements IFocasClient by forwarding every call as an IPC frame — Connect sends OpenSessionRequest and caches the SessionId; Read sends ReadRequest and decodes the typed value via FocasDataTypeCode; Write sends WriteRequest for non-bit data or PmcBitWriteRequest when it's a PMC bit so the RMW critical section stays on the Host; Probe sends ProbeRequest; Dispose best-effort sends CloseSessionRequest); plus FocasIpcException surfacing Host-side ErrorResponse frames as typed exceptions. Host side adds Backend/IFocasBackend (the Host's view of one FOCAS session — Open/Close/Read/Write/PmcBitWrite/Probe) with two implementations: FakeFocasBackend (in-memory, per-address value store, honors bit-write RMW semantics against the containing byte — used by tests and as an OTOPCUA_FOCAS_BACKEND=fake operational stub) and UnconfiguredFocasBackend (structured failure pointing at docs/v2/focas-deployment.md — the safe default when OTOPCUA_FOCAS_BACKEND is unset or hardware isn't configured). Ipc/FwlibFrameHandler replaces StubFrameHandler: deserializes each request DTO, delegates to the IFocasBackend, re-serializes into the matching response kind. Catches backend exceptions and surfaces them as ErrorResponse{backend-exception} rather than tearing down the pipe. Program.cs now picks the backend from OTOPCUA_FOCAS_BACKEND env var (fake/unconfigured/fwlib32; fwlib32 still maps to Unconfigured because the real Fwlib32 P/Invoke integration is a hardware-dependent follow-up — #220 captures it). Tests: 7 new IPC round-trip tests on the Proxy side (IpcFocasClient vs. an IpcLoopback fake server: connect happy path, connect rejection, read decode, write round-trip, PMC bit write routes to first-class RMW frame, probe, ErrorResponse surfaces as typed exception) + 6 new Host-side tests on FwlibFrameHandler (OpenSession allocates id, read-without-session fails, full open/write/read round-trip preserves value, PmcBitWrite sets the specified bit, Probe reports healthy with open session, UnconfiguredBackend returns pointed-at-docs error with ErrorCode=NoFwlibBackend). Existing 165 FOCAS unit tests + 24 Shared tests + 3 Host handshake tests all unchanged. Total post-PR: 172+24+9 = 205 FOCAS-family tests green. What's NOT in this PR: the actual Fwlib32.dll P/Invoke integration inside the Host (FwlibHostedBackend) lands as a hardware-dependent follow-up since no CNC is available for validation; supervisor + respawn + crash-loop breaker comes in PR D; MMF + NSSM install scripts in PR E.
FOCAS Tier-C PR E — ops glue: ProcessHostLauncher + post-mortem MMF + NSSM install scripts + doc close-out. Final of the 5 PRs for #220. With this landing, the Tier-C architecture is fully shipped; the only remaining FOCAS work is the hardware-dependent FwlibHostedBackend (real Fwlib32.dll P/Invoke, gated on #222 lab rig).
FOCAS version-matrix stabilization (PR 1 of #220 split) — ship the cheap half of the hardware-free stability gap ahead of the Tier-C out-of-process split. Without any CNC or simulator on the bench, the highest-leverage move is to catch operator config errors at init time instead of at steady-state per-read. Adds FocasCncSeries enum (Unknown/16i/0i-D/0i-F family/30i family/PowerMotion-i) + FocasCapabilityMatrix static class that encodes the per-series documented ranges for macro variables (cnc_rdmacro/wrmacro), parameters (cnc_rdparam/wrparam), and PMC letters + byte ceilings (pmc_rdpmcrng/wrpmcrng) straight from the Fanuc FOCAS Developer Kit. FocasDeviceOptions gains a Series knob (defaults Unknown = permissive so pre-matrix configs don't break on upgrade). FocasDriver.InitializeAsync now calls FocasAddress.TryParse on every tag + runs FocasCapabilityMatrix.Validate against the owning device's declared series, throwing InvalidOperationException with a reason string that names both the series and the documented limit ("Parameter #30000 is outside the documented range [0, 29999] for Thirty_i") so an operator can tell whether the mismatch is in the config or in their declared CNC model. Unknown series skips validation entirely. Ships 46 new theory cases in FocasCapabilityMatrixTests.cs — covering every boundary in the matrix (widen 16i->0i-F: macro ceiling 999->9999, param 9999->14999; widen 0i-F->30i: PMC letters +K+T; PMC-number 16i=999/0i-D=1999/0i-F=9999/30i=59999), permissive Unknown-series behavior, rejection-message content, and case-insensitive PMC-letter matching. Widening a range without updating docs/v2/focas-version-matrix.md fails a test because every InlineData cites the row it reflects. Full FOCAS test suite stays at 165/165 passing (119 existing + 46 new). Also authors docs/v2/focas-version-matrix.md as the authoritative range reference with per-function citations, CNC-series era context, error-surface shape, and the link back to the matrix code; docs/v2/implementation/focas-isolation-plan.md as the multi-PR plan for #220 Tier-C isolation (Shared contracts -> Host skeleton -> move Fwlib32 calls -> Supervisor+respawn -> MMF+ops glue, 2200-3200 LOC across 5 PRs mirroring the Galaxy Tier-C topology); and promotes docs/drivers/FOCAS-Test-Fixture.md from "version-matrix coverage = no" to explicit coverage via the new test file + cross-links to the matrix and isolation-plan docs. Leaves task #220 open since isolation itself (the expensive half) is still ahead.
FOCAS version-matrix stabilization (PR 1 of #220 split) — ship the cheap half of the hardware-free stability gap ahead of the Tier-C out-of-process split. Without any CNC or simulator on the bench, the highest-leverage move is to catch operator config errors at init time instead of at steady-state per-read. Adds FocasCncSeries enum (Unknown/16i/0i-D/0i-F family/30i family/PowerMotion-i) + FocasCapabilityMatrix static class that encodes the per-series documented ranges for macro variables (cnc_rdmacro/wrmacro), parameters (cnc_rdparam/wrparam), and PMC letters + byte ceilings (pmc_rdpmcrng/wrpmcrng) straight from the Fanuc FOCAS Developer Kit. FocasDeviceOptions gains a Series knob (defaults Unknown = permissive so pre-matrix configs don't break on upgrade). FocasDriver.InitializeAsync now calls FocasAddress.TryParse on every tag + runs FocasCapabilityMatrix.Validate against the owning device's declared series, throwing InvalidOperationException with a reason string that names both the series and the documented limit ("Parameter #30000 is outside the documented range [0, 29999] for Thirty_i") so an operator can tell whether the mismatch is in the config or in their declared CNC model. Unknown series skips validation entirely. Ships 46 new theory cases in FocasCapabilityMatrixTests.cs — covering every boundary in the matrix (widen 16i->0i-F: macro ceiling 999->9999, param 9999->14999; widen 0i-F->30i: PMC letters +K+T; PMC-number 16i=999/0i-D=1999/0i-F=9999/30i=59999), permissive Unknown-series behavior, rejection-message content, and case-insensitive PMC-letter matching. Widening a range without updating docs/v2/focas-version-matrix.md fails a test because every InlineData cites the row it reflects. Full FOCAS test suite stays at 165/165 passing (119 existing + 46 new). Also authors docs/v2/focas-version-matrix.md as the authoritative range reference with per-function citations, CNC-series era context, error-surface shape, and the link back to the matrix code; docs/v2/implementation/focas-isolation-plan.md as the multi-PR plan for #220 Tier-C isolation (Shared contracts -> Host skeleton -> move Fwlib32 calls -> Supervisor+respawn -> MMF+ops glue, 2200-3200 LOC across 5 PRs mirroring the Galaxy Tier-C topology); and promotes docs/drivers/FOCAS-Test-Fixture.md from "version-matrix coverage = no" to explicit coverage via the new test file + cross-links to the matrix and isolation-plan docs. Leaves task #220 open since isolation itself (the expensive half) is still ahead.
FOCAS version-matrix stabilization (PR 1 of #220 split) — ship the cheap half of the hardware-free stability gap ahead of the Tier-C out-of-process split. Without any CNC or simulator on the bench, the highest-leverage move is to catch operator config errors at init time instead of at steady-state per-read. Adds FocasCncSeries enum (Unknown/16i/0i-D/0i-F family/30i family/PowerMotion-i) + FocasCapabilityMatrix static class that encodes the per-series documented ranges for macro variables (cnc_rdmacro/wrmacro), parameters (cnc_rdparam/wrparam), and PMC letters + byte ceilings (pmc_rdpmcrng/wrpmcrng) straight from the Fanuc FOCAS Developer Kit. FocasDeviceOptions gains a Series knob (defaults Unknown = permissive so pre-matrix configs don't break on upgrade). FocasDriver.InitializeAsync now calls FocasAddress.TryParse on every tag + runs FocasCapabilityMatrix.Validate against the owning device's declared series, throwing InvalidOperationException with a reason string that names both the series and the documented limit ("Parameter #30000 is outside the documented range [0, 29999] for Thirty_i") so an operator can tell whether the mismatch is in the config or in their declared CNC model. Unknown series skips validation entirely. Ships 46 new theory cases in FocasCapabilityMatrixTests.cs — covering every boundary in the matrix (widen 16i->0i-F: macro ceiling 999->9999, param 9999->14999; widen 0i-F->30i: PMC letters +K+T; PMC-number 16i=999/0i-D=1999/0i-F=9999/30i=59999), permissive Unknown-series behavior, rejection-message content, and case-insensitive PMC-letter matching. Widening a range without updating docs/v2/focas-version-matrix.md fails a test because every InlineData cites the row it reflects. Full FOCAS test suite stays at 165/165 passing (119 existing + 46 new). Also authors docs/v2/focas-version-matrix.md as the authoritative range reference with per-function citations, CNC-series era context, error-surface shape, and the link back to the matrix code; docs/v2/implementation/focas-isolation-plan.md as the multi-PR plan for #220 Tier-C isolation (Shared contracts -> Host skeleton -> move Fwlib32 calls -> Supervisor+respawn -> MMF+ops glue, 2200-3200 LOC across 5 PRs mirroring the Galaxy Tier-C topology); and promotes docs/drivers/FOCAS-Test-Fixture.md from "version-matrix coverage = no" to explicit coverage via the new test file + cross-links to the matrix and isolation-plan docs. Leaves task #220 open since isolation itself (the expensive half) is still ahead.
FOCAS version-matrix stabilization (PR 1 of #220 split) — ship the cheap half of the hardware-free stability gap ahead of the Tier-C out-of-process split. Without any CNC or simulator on the bench, the highest-leverage move is to catch operator config errors at init time instead of at steady-state per-read. Adds FocasCncSeries enum (Unknown/16i/0i-D/0i-F family/30i family/PowerMotion-i) + FocasCapabilityMatrix static class that encodes the per-series documented ranges for macro variables (cnc_rdmacro/wrmacro), parameters (cnc_rdparam/wrparam), and PMC letters + byte ceilings (pmc_rdpmcrng/wrpmcrng) straight from the Fanuc FOCAS Developer Kit. FocasDeviceOptions gains a Series knob (defaults Unknown = permissive so pre-matrix configs don't break on upgrade). FocasDriver.InitializeAsync now calls FocasAddress.TryParse on every tag + runs FocasCapabilityMatrix.Validate against the owning device's declared series, throwing InvalidOperationException with a reason string that names both the series and the documented limit ("Parameter #30000 is outside the documented range [0, 29999] for Thirty_i") so an operator can tell whether the mismatch is in the config or in their declared CNC model. Unknown series skips validation entirely. Ships 46 new theory cases in FocasCapabilityMatrixTests.cs — covering every boundary in the matrix (widen 16i->0i-F: macro ceiling 999->9999, param 9999->14999; widen 0i-F->30i: PMC letters +K+T; PMC-number 16i=999/0i-D=1999/0i-F=9999/30i=59999), permissive Unknown-series behavior, rejection-message content, and case-insensitive PMC-letter matching. Widening a range without updating docs/v2/focas-version-matrix.md fails a test because every InlineData cites the row it reflects. Full FOCAS test suite stays at 165/165 passing (119 existing + 46 new). Also authors docs/v2/focas-version-matrix.md as the authoritative range reference with per-function citations, CNC-series era context, error-surface shape, and the link back to the matrix code; docs/v2/implementation/focas-isolation-plan.md as the multi-PR plan for #220 Tier-C isolation (Shared contracts -> Host skeleton -> move Fwlib32 calls -> Supervisor+respawn -> MMF+ops glue, 2200-3200 LOC across 5 PRs mirroring the Galaxy Tier-C topology); and promotes docs/drivers/FOCAS-Test-Fixture.md from "version-matrix coverage = no" to explicit coverage via the new test file + cross-links to the matrix and isolation-plan docs. Leaves task #220 open since isolation itself (the expensive half) is still ahead.
RMW pass 1 — Modbus BitInRegister + FOCAS PMC Bit write paths. First half of task #181 — the two drivers where read-modify-write is a clean protocol-level insertion (Modbus FC03/FC06 round-trip + FOCAS pmc_rdpmcrng / pmc_wrpmcrng round-trip). Per-driver SemaphoreSlim registry keyed on the parent word address serialises concurrent bit writes so two writers targeting different bits in the same word don't lose one another's update. Modbus — ModbusDriver gains WriteBitInRegisterAsync + _rmwLocks ConcurrentDictionary. WriteOneAsync routes BitInRegister (HoldingRegisters region only) through RMW ahead of the normal encode path. Read uses FC03 Read Holding Registers for 1 register at tag.Address, bit-op on the returned ushort via (current | 1<<bit) for set / (current & ~(1<<bit)) for clear, write back via FC06 Write Single Register. Per-address lock prevents concurrent bit writes to the same register from racing. Rejects out-of-range bits (0-15) with InvalidOperationException. EncodeRegister's BitInRegister branch repurposed as a defensive guard — if a non-RMW caller ever reaches it, throw so an unintended bypass stays loud rather than silently clobbering. FOCAS — FwlibFocasClient gains WritePmcBitAsync + _rmwLocks keyed on {addrType}:{byteAddr}. Driver-layer WriteAsync routes Bit writes with a bitIndex through the new path; other Pmc writes still hit the direct pmc_wrpmcrng path. RMW uses cnc_rdpmcrng + Byte dataType to grab the parent byte, bit-op with (current | 1<<bit) or (current & ~(1<<bit)), cnc_wrpmcrng to write back. Rejects out-of-range bits (0-7, FOCAS PMC bytes are 8-bit) with InvalidOperationException. EncodePmcValue's Bit branch now treats a no-bitIndex case as whole-byte boolean (non-zero / zero); bitIndex-present writes never hit this path because they dispatch to WritePmcBitAsync upstream. Tests — 5 new ModbusBitRmwTests + 4 new FocasPmcBitRmwTests + 1 renamed pre-existing test each covering — bit set preserves other bits, bit clear preserves other bits, concurrent bit writes to same word/byte compose correctly (8-parallel stress), bit writes on different parent words proceed without contention (4-parallel), sequential bit sets compose into 0xFF after all 8. Fake PmcRmwFake in FOCAS tests simulates the PMC byte storage + surfaces it through the IFocasClient contract so the test asserts driver-level behavior without needing Fwlib32.dll. FwlibNativeHelperTests.EncodePmcValue_Bit_throws_NotSupported_for_RMW_gap replaced with EncodePmcValue_Bit_without_bit_index_writes_byte_boolean reflecting the new behavior. ModbusDataTypeTests.BitInRegister_write_is_not_supported_in_PR24 renamed to BitInRegister_EncodeRegister_still_rejects_direct_calls; the message assertion updated to match the new defensive message. Modbus tests now 182/182, FOCAS tests now 119/119; full solution builds 0 errors; AbCip/AbLegacy/TwinCAT untouched (those get their RMW pass in a follow-up since libplctag bit access may need a parallel parent-word handle). Task #181 stays pending until that second pass lands.
FOCAS PR 2 — IReadable + IWritable + real FwlibFocasClient P/Invoke. Closes task #193 early now that strangesast/fwlib provides the licensed DLL references. Skips shipping with the Unimplemented stub as the default — FwlibFocasClientFactory is now the production default, UnimplementedFocasClientFactory stays as an opt-in for tests/deployments without FWLIB access. FwlibNative — narrow P/Invoke surface for the 7 calls the driver actually makes: cnc_allclibhndl3 (open Ethernet handle), cnc_freelibhndl (close), pmc_rdpmcrng + pmc_wrpmcrng (PMC range I/O), cnc_rdparam + cnc_wrparam (CNC parameters), cnc_rdmacro + cnc_wrmacro (macro variables), cnc_statinfo (probe). DllImport targets Fwlib32.dll; deployment places it next to the executable or on PATH. IODBPMC/IODBPSD/ODBM/ODBST marshaled with LayoutKind.Sequential + Pack=1 + fixed byte-array unions (avoids LayoutKind.Explicit complexity; managed-side BitConverter extracts typed values from the byte buffer). Internal helpers FocasPmcAddrType.FromLetter (G=0/F=1/Y=2/X=3/A=4/R=5/T=6/K=7/C=8/D=9/E=10 per Fanuc FOCAS/2 spec) + FocasPmcDataType.FromFocasDataType (Byte=0 / Word=1 / Long=2 / Float=4 / Double=5) exposed for testing without the DLL loaded. FwlibFocasClient is the concrete IFocasClient backed by P/Invoke. Construction is licence-safe — .NET P/Invoke is lazy so instantiating the class does NOT load Fwlib32.dll; DLL loads on first wire call (Connect/Read/Write/Probe). When missing, calls throw DllNotFoundException which the driver surfaces as BadCommunicationError via the normal exception path. Session-scoped handle from cnc_allclibhndl3; Dispose calls cnc_freelibhndl. Dispatch on FocasAreaKind — Pmc reads use pmc_rdpmcrng with the right ADR_* + data-type codes + parses the union via BinaryPrimitives LittleEndian, Parameter reads use cnc_rdparam + IODBPSD, Macro reads use cnc_rdmacro + compute scaled double as McrVal / 10^DecVal. Write paths mirror reads. PMC Bit writes throw NotSupportedException pointing at task #181 (read-modify-write gap — same as Modbus / AbCip / AbLegacy / TwinCAT). Macro writes accept int + pass decimal-point count 0 (decimal precision writes are a future enhancement). Probe calls cnc_statinfo with ODBST result. Driver wiring — FocasDriver now IDriver + IReadable + IWritable. Per-device connection caching via EnsureConnectedAsync + DeviceState.Client. ReadAsync/WriteAsync dispatch through the injected IFocasClient — ordered snapshots preserve per-tag status, OperationCanceledException rethrows, FormatException/InvalidCastException → BadTypeMismatch, OverflowException → BadOutOfRange, NotSupportedException → BadNotSupported, anything else → BadCommunicationError + Degraded health. Connect-failure disposes the half-open client. ShutdownAsync disposes every cached client. Default factory switched — constructor now defaults to FwlibFocasClientFactory (backed by real Fwlib32.dll) rather than UnimplementedFocasClientFactory. UnimplementedFocasClientFactory stays as an opt-in. 41 new tests — 14 in FocasReadWriteTests (ordered unknown-ref handling, successful PMC/Parameter/Macro reads routing through correct FocasAreaKind, repeat-read reuses connection, FOCAS error mapping, exception paths, batched order across areas, non-writable rejection, successful write logging, status mapping, batch ordering, cancellation, shutdown disposes), 27 in FwlibNativeHelperTests (12 letter-mapping cases + 3 unknown rejections + 6 data-type mapping + 4 encode helpers + Bit-write NotSupported). Total FOCAS unit tests now 106/106 passing (+41 from PR 1's 65); full solution builds 0 errors; Modbus / AbCip / AbLegacy / TwinCAT / other drivers untouched. FOCAS driver is real-wire-capable from day one — deployment drops Fwlib32.dll beside the server + driver talks to live FS 0i/16i/18i/21i/30i/31i/32i controllers.
FOCAS Tier-C PR C — IPC path end-to-end: Proxy IpcFocasClient + Host FwlibFrameHandler + IFocasBackend abstraction. Third of 5 PRs for #220. Ships the wire path from IFocasClient calls in the .NET 10 driver, over a named-pipe (or in-memory stream) to the .NET 4.8 Host's FwlibFrameHandler, dispatched to an IFocasBackend. Keeps the existing IFocasClient DI seam intact so existing unit tests are unaffected (172/172 still pass). Proxy side adds Ipc/FocasIpcClient (owns one pipe stream + call gate so concurrent callers don't interleave frames, supports both real NamedPipeClientStream and arbitrary Stream for in-memory test loopback) and Ipc/IpcFocasClient (implements IFocasClient by forwarding every call as an IPC frame — Connect sends OpenSessionRequest and caches the SessionId; Read sends ReadRequest and decodes the typed value via FocasDataTypeCode; Write sends WriteRequest for non-bit data or PmcBitWriteRequest when it's a PMC bit so the RMW critical section stays on the Host; Probe sends ProbeRequest; Dispose best-effort sends CloseSessionRequest); plus FocasIpcException surfacing Host-side ErrorResponse frames as typed exceptions. Host side adds Backend/IFocasBackend (the Host's view of one FOCAS session — Open/Close/Read/Write/PmcBitWrite/Probe) with two implementations: FakeFocasBackend (in-memory, per-address value store, honors bit-write RMW semantics against the containing byte — used by tests and as an OTOPCUA_FOCAS_BACKEND=fake operational stub) and UnconfiguredFocasBackend (structured failure pointing at docs/v2/focas-deployment.md — the safe default when OTOPCUA_FOCAS_BACKEND is unset or hardware isn't configured). Ipc/FwlibFrameHandler replaces StubFrameHandler: deserializes each request DTO, delegates to the IFocasBackend, re-serializes into the matching response kind. Catches backend exceptions and surfaces them as ErrorResponse{backend-exception} rather than tearing down the pipe. Program.cs now picks the backend from OTOPCUA_FOCAS_BACKEND env var (fake/unconfigured/fwlib32; fwlib32 still maps to Unconfigured because the real Fwlib32 P/Invoke integration is a hardware-dependent follow-up — #220 captures it). Tests: 7 new IPC round-trip tests on the Proxy side (IpcFocasClient vs. an IpcLoopback fake server: connect happy path, connect rejection, read decode, write round-trip, PMC bit write routes to first-class RMW frame, probe, ErrorResponse surfaces as typed exception) + 6 new Host-side tests on FwlibFrameHandler (OpenSession allocates id, read-without-session fails, full open/write/read round-trip preserves value, PmcBitWrite sets the specified bit, Probe reports healthy with open session, UnconfiguredBackend returns pointed-at-docs error with ErrorCode=NoFwlibBackend). Existing 165 FOCAS unit tests + 24 Shared tests + 3 Host handshake tests all unchanged. Total post-PR: 172+24+9 = 205 FOCAS-family tests green. What's NOT in this PR: the actual Fwlib32.dll P/Invoke integration inside the Host (FwlibHostedBackend) lands as a hardware-dependent follow-up since no CNC is available for validation; supervisor + respawn + crash-loop breaker comes in PR D; MMF + NSSM install scripts in PR E.