Files
Joseph Doherty
3892555631
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.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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 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 PR 3 — ITagDiscovery + ISubscribable + IHostConnectivityProbe + IPerCallHostResolver. Completes the FOCAS driver — 7-interface capability set matching AbCip/AbLegacy/TwinCAT (minus IAlarmSource — Fanuc CNC alarms live in a different API surface, tracked as a future-phase concern). ITagDiscovery emits pre-declared tags under a FOCAS root + per-device sub-folder keyed on the canonical focas://host:port string with DeviceName fallback. Writable → Operate, non-writable → ViewOnly. No native FOCAS symbol browsing — CNCs don't expose a tag catalogue the way Logix or TwinCAT do; operators declare addresses explicitly. ISubscribable consumes the shared PollGroupEngine — 5th consumer of the engine after Modbus + AbCip + AbLegacy + TwinCAT-poll-mode. 100ms interval floor inherited. FOCAS has no native notification/subscription protocol (unlike TwinCAT ADS), so polling is the only option — every subscribed tag round-trips through cnc_rdpmcrng / cnc_rdparam / cnc_rdmacro on each tick. IHostConnectivityProbe uses the existing IFocasClient.ProbeAsync which in the real FwlibFocasClient calls cnc_statinfo (cheap handshake returning ODBST with tmmode/aut/run/motion/alarm state). Probe loop runs when Enabled=true, catches OperationCanceledException during shutdown, falls through to Stopped on exceptions, emits Running/Stopped transitions via OnHostStatusChanged with the canonical focas://host:port as the host-name key. Same-state spurious-event guard under per-device lock. IPerCallHostResolver maps tag full-ref to DeviceHostAddress for Phase 6.1 bulkhead/breaker keying per plan decision #144 — unknown refs fall back to first device, no devices → DriverInstanceId. ShutdownAsync now disposes PollGroupEngine + cancels/disposes per-device probe CTS + disposes cached clients. DeviceState gains ProbeLock / HostState / HostStateChangedUtc / ProbeCts matching the shape used by AbCip/AbLegacy/TwinCAT. 9 new unit tests in FocasCapabilityTests — discovery tag emission with correct SecurityClassification, subscription initial poll raises OnDataChange, shutdown cancels subscriptions, GetHostStatuses entry-per-device, probe Running / Stopped transitions, ResolveHost for known / unknown / no-devices paths. FocasScaffoldingTests updated with Probe.Enabled=false where the default factory would otherwise try to load Fwlib32.dll during the probe-loop spinup. Total FOCAS unit tests now 115/115 passing (+9 from PR 2's 106); full solution builds 0 errors; Modbus / AbCip / AbLegacy / TwinCAT / other drivers untouched. FOCAS driver is real-wire-capable end-to-end — read / write / discover / subscribe / probe / host-resolve for Fanuc FS 0i/16i/18i/21i/30i/31i/32i/Series 35i/Power Mate i controllers once deployment drops Fwlib32.dll beside the server. Closes task #120 subtask FOCAS.
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 PR 3 — ITagDiscovery + ISubscribable + IHostConnectivityProbe + IPerCallHostResolver. Completes the FOCAS driver — 7-interface capability set matching AbCip/AbLegacy/TwinCAT (minus IAlarmSource — Fanuc CNC alarms live in a different API surface, tracked as a future-phase concern). ITagDiscovery emits pre-declared tags under a FOCAS root + per-device sub-folder keyed on the canonical focas://host:port string with DeviceName fallback. Writable → Operate, non-writable → ViewOnly. No native FOCAS symbol browsing — CNCs don't expose a tag catalogue the way Logix or TwinCAT do; operators declare addresses explicitly. ISubscribable consumes the shared PollGroupEngine — 5th consumer of the engine after Modbus + AbCip + AbLegacy + TwinCAT-poll-mode. 100ms interval floor inherited. FOCAS has no native notification/subscription protocol (unlike TwinCAT ADS), so polling is the only option — every subscribed tag round-trips through cnc_rdpmcrng / cnc_rdparam / cnc_rdmacro on each tick. IHostConnectivityProbe uses the existing IFocasClient.ProbeAsync which in the real FwlibFocasClient calls cnc_statinfo (cheap handshake returning ODBST with tmmode/aut/run/motion/alarm state). Probe loop runs when Enabled=true, catches OperationCanceledException during shutdown, falls through to Stopped on exceptions, emits Running/Stopped transitions via OnHostStatusChanged with the canonical focas://host:port as the host-name key. Same-state spurious-event guard under per-device lock. IPerCallHostResolver maps tag full-ref to DeviceHostAddress for Phase 6.1 bulkhead/breaker keying per plan decision #144 — unknown refs fall back to first device, no devices → DriverInstanceId. ShutdownAsync now disposes PollGroupEngine + cancels/disposes per-device probe CTS + disposes cached clients. DeviceState gains ProbeLock / HostState / HostStateChangedUtc / ProbeCts matching the shape used by AbCip/AbLegacy/TwinCAT. 9 new unit tests in FocasCapabilityTests — discovery tag emission with correct SecurityClassification, subscription initial poll raises OnDataChange, shutdown cancels subscriptions, GetHostStatuses entry-per-device, probe Running / Stopped transitions, ResolveHost for known / unknown / no-devices paths. FocasScaffoldingTests updated with Probe.Enabled=false where the default factory would otherwise try to load Fwlib32.dll during the probe-loop spinup. Total FOCAS unit tests now 115/115 passing (+9 from PR 2's 106); full solution builds 0 errors; Modbus / AbCip / AbLegacy / TwinCAT / other drivers untouched. FOCAS driver is real-wire-capable end-to-end — read / write / discover / subscribe / probe / host-resolve for Fanuc FS 0i/16i/18i/21i/30i/31i/32i/Series 35i/Power Mate i controllers once deployment drops Fwlib32.dll beside the server. Closes task #120 subtask FOCAS.
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 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 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.