Web verification (2026-04-25) against current vendor docs surfaced concrete grammar conflicts in the v1 suffix grammar shipped in #137. Hard cutover before the Admin UI rolls out widely so users don't paste `:I` from a Wonderware spreadsheet and silently get wrong-typed reads. Sources: - Wonderware DASMBTCP user guide https://cdn.logic-control.com/media/DASMBTCP.pdf - Ignition Modbus addressing (8.1) https://www.docs.inductiveautomation.com/docs/8.1/ignition-modules/opc-ua/opc-ua-drivers/modbus/modbus-addressing Type-code changes: | Code | Pre-#146 | Post-#146 | Vendor reference | |--------|----------|------------|------------------------------| | `:S` | (n/a) | Int16 | Wonderware DASMBTCP `S` | | `:US` | (n/a) | UInt16 | Ignition `HRUS` | | `:I` | Int16 | **Int32** | Wonderware `I` + Ignition `HRI` | | `:UI` | UInt16 | **UInt32** | Ignition `HRUI` | | `:I_64` | (n/a) | Int64 | Ignition `HRI_64` | | `:UI_64` | (n/a) | UInt64 | Ignition `HRUI_64` | | `:BCD_32`| (n/a) | BCD32 | Ignition `HRBCD_32` | Codes REMOVED (no clear vendor precedent + conflict with the new mapping): `:DI`, `:L`, `:UDI`, `:UL`, `:LI`, `:ULI`, `:LBCD`. Pre-#146 configs that use them get an "Unknown type code" diagnostic at parse time so users get a fast surface-level error rather than silent wrong-typed reads. Codes UNCHANGED (already vendor-aligned): `:BOOL`, `:F`, `:D`, `:BCD`, `:STR<n>`. Modicon 5/6-digit + mnemonic regions (HR/IR/C/DI) + bit suffix `.N` are also unchanged. Defaults: - Coils / DiscreteInputs → `BOOL` (unchanged) - HoldingRegisters / InputRegisters with no explicit type → Int16 (matches Ignition's bare `HR` default) Byte-order mnemonics (`:ABCD` / `:CDAB` / `:BADC` / `:DCBA`) are kept but documented as OtOpcUa-specific — they aren't in any major vendor's per-tag address string. Ignition uses a `-R` suffix per prefix; Wonderware configures word-order at the topic level. Tests: - 12 Type_Codes_Parse rows updated to assert the new mappings. - New Removed_Aliases_Are_Rejected (×7) confirms each pre-#146 alias now fails fast with "Unknown type code". - Worked_Example_Int16_Array uses the new `:S` code. - New Worked_Example_Int32_Array_Via_I_Code documents the `:I = Int32` vendor-alignment intent so a future "fix" doesn't accidentally regress. - Unknown_Type_Code_Rejected_With_Catalog updated to match the new error message ("Valid: BOOL, S, US, I, ..."). Docs: - docs/v2/modbus-addressing.md — table replaced with the post-#146 codes, each row cites its Wonderware / Ignition reference. New "Codes removed in #146" subsection documents the cutover. - docs/Driver.Modbus.Cli.md — example grammar list updated; explicit type-code reminder appended. 114 addressing tests + 231 driver tests still green. Solution build clean.
OtOpcUa documentation
Two tiers of documentation live here:
- Current reference at the top level (
docs/*.md) — describes what's shipped today. Start here for operator + integrator reference. - Implementation history + design notes at
docs/v2/*.md— the authoritative plan + decision log the current reference is built from. Start here when you need the why behind an architectural choice, or when a top-level doc says "see plan.md § X".
The project was originally called LmxOpcUa (a single-driver Galaxy/MXAccess OPC UA server) and has since become OtOpcUa, a multi-driver OPC UA server platform. Any lingering LmxOpcUa-string in a path you see in docs is a deliberate residual (executable name lmxopcua-cli, client PKI folder {LocalAppData}/LmxOpcUaClient/) — fixing those requires migration shims + is tracked as follow-ups.
Platform overview
- Core owns the OPC UA stack, address space, session/security/subscription machinery.
- Drivers plug in via capability interfaces in
ZB.MOM.WW.OtOpcUa.Core.Abstractions:IDriver,IReadable,IWritable,ITagDiscovery,ISubscribable,IHostConnectivityProbe,IAlarmSource,IHistoryProvider,IPerCallHostResolver. Each driver opts into whichever it supports. - Server is the OPC UA endpoint process (net10, x64). Hosts every driver except Galaxy in-process; talks to Galaxy via a named pipe because MXAccess COM is 32-bit-only.
- Admin is the Blazor Server operator UI (net10, x64). Owns the Config DB draft/publish flow, ACL + role-grant authoring, fleet status +
/metricsscrape endpoint. - Galaxy.Host is a .NET Framework 4.8 x86 Windows service that wraps MXAccess COM on an STA thread for the Galaxy driver.
Where to find what
Architecture + data-path reference
| Doc | Covers |
|---|---|
| OpcUaServer.md | Top-level server architecture — Core, driver dispatch, Config DB, generations |
| AddressSpace.md | GenericDriverNodeManager + ITagDiscovery + IAddressSpaceBuilder |
| ReadWriteOperations.md | OPC UA Read/Write → CapabilityInvoker → IReadable/IWritable |
| Subscriptions.md | Monitored items → ISubscribable + per-driver subscription refcount |
| AlarmTracking.md | IAlarmSource + AlarmSurfaceInvoker + OPC UA alarm conditions |
| DataTypeMapping.md | Per-driver DriverAttributeInfo → OPC UA variable types |
| IncrementalSync.md | Address-space rebuild on redeploy + sp_ComputeGenerationDiff |
| HistoricalDataAccess.md | IHistoryProvider as a per-driver optional capability |
| VirtualTags.md | Core.Scripting + Core.VirtualTags — Roslyn script sandbox, engine, dispatch alongside driver tags |
| ScriptedAlarms.md | Core.ScriptedAlarms — script-predicate IAlarmSource + Part 9 state machine |
Two Core subsystems are shipped without a dedicated top-level doc; see the section in the linked doc:
| Project | See |
|---|---|
Core.AlarmHistorian |
AlarmTracking.md § Alarm historian sink |
Analyzers (Roslyn OTOPCUA0001) |
security.md § OTOPCUA0001 Analyzer |
Drivers
| Doc | Covers |
|---|---|
| drivers/README.md | Index of the eight shipped drivers + capability matrix |
| drivers/Galaxy.md | Galaxy driver — MXAccess bridge, Host/Proxy split, named-pipe IPC |
| drivers/Galaxy-Repository.md | Galaxy-specific discovery via the ZB SQL database |
For Modbus / S7 / AB CIP / AB Legacy / TwinCAT / FOCAS / OPC UA Client specifics, see v2/driver-specs.md.
Operational
| Doc | Covers |
|---|---|
| Configuration.md | appsettings bootstrap + Config DB + Admin UI draft/publish |
| security.md | Transport security profiles, LDAP auth, ACL trie, role grants, OTOPCUA0001 analyzer |
| Redundancy.md | RedundancyCoordinator, ServiceLevelCalculator, apply-lease, Prometheus metrics |
| ServiceHosting.md | Three-process deploy (Server + Admin + Galaxy.Host) install/uninstall |
| StatusDashboard.md | Pointer — superseded by v2/admin-ui.md |
Client tooling
| Doc | Covers |
|---|---|
| Client.CLI.md | otopcua-cli — OPC UA command-line client |
| Client.UI.md | Avalonia desktop client |
| DriverClis.md | Driver test-client CLIs — index + shared commands |
| Driver.Modbus.Cli.md | otopcua-modbus-cli — Modbus-TCP |
| Driver.AbCip.Cli.md | otopcua-abcip-cli — ControlLogix / CompactLogix / Micro800 / GuardLogix |
| Driver.AbLegacy.Cli.md | otopcua-ablegacy-cli — SLC / MicroLogix / PLC-5 (PCCC) |
| Driver.S7.Cli.md | otopcua-s7-cli — Siemens S7-300 / S7-400 / S7-1200 / S7-1500 |
| Driver.TwinCAT.Cli.md | otopcua-twincat-cli — Beckhoff TwinCAT 2/3 ADS |
| Driver.FOCAS.Cli.md | otopcua-focas-cli — Fanuc FOCAS/2 CNC |
Requirements
| Doc | Covers |
|---|---|
| reqs/HighLevelReqs.md | HLRs — numbered system-level requirements |
| reqs/OpcUaServerReqs.md | OPC UA server-layer reqs |
| reqs/ServiceHostReqs.md | Per-process hosting reqs |
| reqs/ClientRequirements.md | Client CLI + UI reqs |
| reqs/GalaxyRepositoryReqs.md | Galaxy-scoped repository reqs |
| reqs/MxAccessClientReqs.md | Galaxy-scoped MXAccess reqs |
| reqs/StatusDashboardReqs.md | Pointer — superseded by Admin UI |
Implementation history (docs/v2/)
Design decisions + phase plans + execution notes. Load-bearing cross-references from the top-level docs:
- v2/plan.md — authoritative v2 vision doc + numbered decision log (referenced as "decision #N" elsewhere)
- v2/admin-ui.md — Admin UI spec
- v2/acl-design.md — data-plane ACL + permission-trie design (Phase 6.2)
- v2/config-db-schema.md — Config DB schema reference
- v2/driver-specs.md — per-driver addressing + quirks for every shipped protocol
- v2/dev-environment.md — dev-box bootstrap
- v2/test-data-sources.md — integration-test simulator matrix (includes the pinned libplctag
ab_serverversion for AB CIP tests) - v2/implementation/phase--.md — per-phase execution plans with exit-gate evidence