Files touched — docs/drivers/Modbus-Test-Fixture.md dropped the key-files pointer at deleted Pymodbus/ + flipped "primary launcher is Docker, native fallback retained" framing to "Docker is the only supported launch path" (matching the code). docs/v2/dev-environment.md dropped the "skips both Docker + native-binary paths" parenthetical from AB_SERVER_ENDPOINT + flipped the "Native fallbacks" subsection to a one-liner that says Docker is the only supported path. docs/v2/modbus-test-plan.md rewrote §Harness from "pip install pymodbus + serve.ps1" setup pattern to "docker compose --profile <…> up" + updated the §PR 43 status bullet to point at Docker/profiles/. docs/v2/test-data-sources.md §"CI fixture (task #180)" rewrote the AB CIP section from "LocateBinary() picks binary off PATH" + GitHub Actions zip-download step to "Docker is the only supported reproducible build path" + docker compose GitHub Actions step; dropped the pinned-version SHA256 table + lock-file reference because the Dockerfile's LIBPLCTAG_TAG build-arg is the new pin. Code docstrings + error messages — these are developer-facing operational text too. ModbusSimulatorFixture SkipReason strings (both branches) now point at `docker compose -f Docker/docker-compose.yml --profile standard up -d` instead of the deleted `Pymodbus\serve.ps1`; doc-comment at the top references Docker/docker-compose.yml. Snap7ServerFixture SkipReason strings + doc-comment point at Docker/docker-compose.yml instead of PythonSnap7/serve.ps1. S7_1500Profile.cs docstring updated. Modbus Dockerfile comment pointing at deleted tests/.../Pymodbus/README.md redirected to docs/drivers/Modbus-Test-Fixture.md. DL205Profile.cs + DL205StringQuirkTests.cs + S7_1500Profile.cs (in Modbus project) docstrings flipped from Pymodbus/*.json references to Docker/profiles/*.json. Left untouched deliberately: docs/v2/implementation/exit-gate-phase-2-closed.md — that's a historical as-of-2026-04-18 snapshot documenting what was skipped at Phase 2 closure; rewriting would lose the date-stamped context. Its "oitc/modbus-server Docker container not started" + "ab_server binary not on PATH" lines describe the fixture landscape that existed at close time, not current operational guidance. Final sweep confirms zero remaining `Pymodbus/` / `PythonSnap7/` / `LocateBinary` / `AbServerSeedTag` / `BuildCliArgs` / `AbServerPlcArg` mentions anywhere in tracked files outside that historical exit-gate doc. Whole-solution build still 0 errors. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Drivers
OtOpcUa is a multi-driver OPC UA server. The Core (ZB.MOM.WW.OtOpcUa.Core + Core.Abstractions + Server) owns the OPC UA stack, address space, session/security/subscription machinery, resilience pipeline, and namespace kinds (Equipment + SystemPlatform). Drivers plug in through capability interfaces defined in src/ZB.MOM.WW.OtOpcUa.Core.Abstractions/:
IDriver— lifecycle (InitializeAsync,ReinitializeAsync,ShutdownAsync,GetHealth)IReadable/IWritable— one-shot reads and writesITagDiscovery— address-space enumerationISubscribable— driver-pushed data-change streamsIHostConnectivityProbe— per-host reachability eventsIPerCallHostResolver— multi-host drivers that route each call to a target endpoint at dispatch timeIAlarmSource— driver-emitted OPC UA A&C eventsIHistoryProvider— raw / processed / at-time / events HistoryRead (see HistoricalDataAccess.md)IRediscoverable— driver-initiated address-space rebuild notifications
Each driver opts into only the capabilities it supports. Every async capability call at the Server dispatch layer goes through CapabilityInvoker (Core/Resilience/CapabilityInvoker.cs), which wraps it in a Polly pipeline keyed on (DriverInstanceId, HostName, DriverCapability). The OTOPCUA0001 analyzer enforces the wrap at build time. Drivers themselves never depend on Polly; they just implement the capability interface and let the Core wrap it.
Driver type metadata is registered at startup in DriverTypeRegistry (src/ZB.MOM.WW.OtOpcUa.Core.Abstractions/DriverTypeRegistry.cs). The registry records each type's allowed namespace kinds (Equipment / SystemPlatform / Simulated), its JSON Schema for DriverConfig / DeviceConfig / TagConfig columns, and its stability tier per docs/v2/driver-stability.md.
Ground-truth driver list
| Driver | Project path | Tier | Wire / library | Capabilities | Notable quirk |
|---|---|---|---|---|---|
| Galaxy | Driver.Galaxy.{Shared, Host, Proxy} |
C | MXAccess COM + aahClientManaged + SqlClient |
IDriver, ITagDiscovery, IReadable, IWritable, ISubscribable, IAlarmSource, IHistoryProvider, IRediscoverable, IHostConnectivityProbe | Out-of-process — Host is its own Windows service (.NET 4.8 x86 for the COM bitness constraint); Proxy talks to Host over a named pipe |
| Modbus TCP | Driver.Modbus |
A | NModbus-derived in-house client | IDriver, ITagDiscovery, IReadable, IWritable, ISubscribable, IHostConnectivityProbe | Polled subscriptions via the shared PollGroupEngine. DL205 PLCs are covered by AddressFormat=DL205 (octal V/X/Y/C/T/CT translation) — no separate driver |
| Siemens S7 | Driver.S7 |
A | S7netplus | IDriver, ITagDiscovery, IReadable, IWritable, ISubscribable, IHostConnectivityProbe | Single S7netplus Plc instance per PLC serialized with SemaphoreSlim — the S7 CPU's comm mailbox is scanned at most once per cycle, so parallel reads don't help |
| AB CIP | Driver.AbCip |
A | libplctag CIP | IDriver, ITagDiscovery, IReadable, IWritable, ISubscribable, IHostConnectivityProbe, IPerCallHostResolver | ControlLogix / CompactLogix. Tag discovery uses the @tags walker to enumerate controller-scoped + program-scoped symbols; UDT member resolution via the UDT template reader |
| AB Legacy | Driver.AbLegacy |
A | libplctag PCCC | IDriver, ITagDiscovery, IReadable, IWritable, ISubscribable, IHostConnectivityProbe, IPerCallHostResolver | SLC 500 / MicroLogix. File-based addressing (N7:0, F8:0) — no symbol table, tag list is user-authored in the config DB |
| TwinCAT | Driver.TwinCAT |
B | Beckhoff TwinCAT.Ads (TcAdsClient) |
IDriver, ITagDiscovery, IReadable, IWritable, ISubscribable, IHostConnectivityProbe, IPerCallHostResolver | The only native-notification driver outside Galaxy — ADS delivers ValueChangedCallback events the driver forwards straight to ISubscribable.OnDataChange without polling. Symbol tree uploaded via SymbolLoaderFactory |
| FOCAS | Driver.FOCAS |
C | FANUC FOCAS2 (Fwlib32.dll P/Invoke) |
IDriver, ITagDiscovery, IReadable, IWritable, ISubscribable, IHostConnectivityProbe, IPerCallHostResolver | Tier C — FOCAS DLL has crash modes that warrant process isolation. CNC-shaped data model (axes, spindle, PMC, macros, alarms) not a flat tag map |
| OPC UA Client | Driver.OpcUaClient |
B | OPCFoundation Opc.Ua.Client |
IDriver, ITagDiscovery, IReadable, IWritable, ISubscribable, IAlarmSource, IHistoryProvider, IHostConnectivityProbe | Gateway/aggregation driver. Opens a single Session against a remote OPC UA server and re-exposes its address space. Owns its own ApplicationConfiguration (distinct from Client.Shared) because it's always-on with keep-alive + TransferSubscriptions across SDK reconnect, not an interactive CLI |
Per-driver documentation
-
Galaxy has its own docs in this folder because the out-of-process architecture + MXAccess COM rules + Galaxy Repository SQL + Historian + runtime probe manager don't fit a single table row:
- Galaxy.md — COM bridge, STA pump, IPC, runtime probes
- Galaxy-Repository.md — ZB SQL reader,
LocalPlatformscope filter, change detection
-
All other drivers share a single per-driver specification in docs/v2/driver-specs.md — addressing, data-type maps, connection settings, and quirks live there. That file is the authoritative per-driver reference; this index points at it rather than duplicating.
Test-fixture coverage maps
Each driver has a dedicated fixture doc that lays out what the integration / unit harness actually covers vs. what's trusted from field deployments. Read the relevant one before claiming "green suite = production-ready" for a driver.
- AB CIP — Dockerized
ab_server(multi-stage build from libplctag source); atomic-read smoke across 4 families; UDT / ALMD / family quirks unit-only - Modbus — Dockerized
pymodbus+ per-family JSON profiles (4 compose profiles); best-covered driver, gaps are error-path-shaped - Siemens S7 — Dockerized
python-snap7server; DB/MB read + write round-trip verified end-to-end on:1102 - AB Legacy — no integration fixture, unit-only via
FakeAbLegacyTag(libplctag PCCC) - TwinCAT — no integration fixture, unit-only via
FakeTwinCATClientwith native-notification harness - FOCAS — no integration fixture, unit-only via
FakeFocasClient; Tier C out-of-process isolation scoped but not shipped - OPC UA Client — no integration fixture, unit-only via mocked
Session; loopback against this repo's own server is the obvious next step - Galaxy — richest harness: E2E Host subprocess + ZB SQL live-smoke + MXAccess opt-in
Related cross-driver docs
- HistoricalDataAccess.md —
IHistoryProviderdispatch, aggregate mapping, continuation points. The Galaxy driver's Aveva Historian implementation is the first; OPC UA Client forwards to the upstream server; other drivers do not implement the interface and returnBadHistoryOperationUnsupported. - AlarmTracking.md —
IAlarmSourceevent model and filtering. - Subscriptions.md — how the Server multiplexes subscriptions onto
ISubscribable.OnDataChange. - docs/v2/driver-stability.md — tier system (A / B / C), shared
CapabilityPolicydefaults per tier × capability,MemoryTrackinghybrid formula, and process-level recycle rules. - docs/v2/plan.md — authoritative vision, architecture decisions, migration strategy.