33054c3275
- docs/drivers/FOCAS.md and docs/v2/implementation/focas-wire-protocol.md pointed at focas-deployment.md and focas-simulator-plan.md, both of which were untracked drafts that have since been removed. Drop the refs (the wire-protocol companion now stands on its own; deployment guidance lives inline in the FOCAS driver doc). - Link the orphan v2 design docs from docs/README.md (multi-host dispatch, v2 release readiness, the historical lmx-followups tracker) and from modbus-test-plan.md (s7.md, mitsubishi.md per-family quirk catalogs, sibling to dl205.md). Surfaced by the doc audit; no content changes. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
136 lines
8.3 KiB
Markdown
136 lines
8.3 KiB
Markdown
# Modbus driver — test plan + device-quirk catalog
|
||
|
||
The Modbus TCP driver unit tests (PRs 21–24) cover the protocol surface against an
|
||
in-memory fake transport. They validate the codec, state machine, and function-code
|
||
routing against a textbook Modbus server. That's necessary but not sufficient: real PLC
|
||
populations disagree with the spec in small, device-specific ways, and a driver that
|
||
passes textbook tests can still misbehave against actual equipment.
|
||
|
||
This doc is the harness-and-quirks playbook. The project it describes lives at
|
||
`tests/ZB.MOM.WW.OtOpcUa.Driver.Modbus.IntegrationTests/` — scaffolded in PR 30 with
|
||
the simulator fixture, DL205 profile stub, and one write/read smoke test. Each
|
||
confirmed DL205 quirk lands in a follow-up PR as a named test in that project.
|
||
|
||
## Harness
|
||
|
||
**Chosen simulator: pymodbus 3.13.0** packaged as a pinned Docker image
|
||
under `tests/.../Modbus.IntegrationTests/Docker/`. See that folder's
|
||
`README.md` for image-build notes + compose profiles. Headline reasons:
|
||
|
||
- **Headless** pure-Python CLI; no Java GUI, runs cleanly on a CI runner.
|
||
- **Maintained** — current stable 3.13.0; ModbusPal 1.6b is abandoned.
|
||
- **All four standard tables** (HR, IR, coils, DI) configurable; ModbusPal
|
||
1.6b only exposed HR + coils.
|
||
- **Built-in actions** (`increment`, `random`, `timestamp`, `uptime`) +
|
||
optional custom-Python actions for declarative dynamic behaviors.
|
||
- **Per-register raw uint16 seeding** — encoding the DL205 string-byte-order
|
||
/ BCD / CDAB-float quirks stays explicit (the quirk math lives in the
|
||
`_quirk` JSON-comment fields next to each register).
|
||
- **Dockerized** — pinned image means the CI simulator surface is
|
||
reproducible + no `pip install` step on the dev box.
|
||
- Defaults to TCP **5020** (matches the compose port-map + the fixture
|
||
default endpoint; sidesteps the Windows Firewall prompt on 502).
|
||
|
||
**Setup pattern**:
|
||
1. `docker compose -f tests\...\Modbus.IntegrationTests\Docker\docker-compose.yml --profile <standard|dl205|mitsubishi|s7_1500> up -d`.
|
||
2. `dotnet test tests\ZB.MOM.WW.OtOpcUa.Driver.Modbus.IntegrationTests` —
|
||
tests auto-skip when the endpoint is unreachable. Default endpoint is
|
||
`localhost:5020`; override via `MODBUS_SIM_ENDPOINT` for a real PLC on its
|
||
native port 502.
|
||
3. `docker compose -f ... --profile <…> down` when finished.
|
||
|
||
## Per-device quirk catalog
|
||
|
||
### AutomationDirect DL205 / DL260
|
||
|
||
First known target device family. **Full quirk catalog with primary-source citations
|
||
and per-quirk integration-test names lives at [`dl205.md`](dl205.md)** — that doc is
|
||
the reference; this section is the testing roadmap.
|
||
|
||
Confirmed quirks (priority order — top items are highest-impact for our driver
|
||
and ship first as PR 41+):
|
||
|
||
| Quirk | Driver impact | Integration-test name |
|
||
|---|---|---|
|
||
| **String packing**: 2 chars/register, **first char in low byte** (opposite of generic Modbus) | `ModbusDataType.String` decoder must be configurable per-device family — current code assumes high-byte-first | `DL205_String_low_byte_first_within_register` |
|
||
| **Word order CDAB** for Int32/UInt32/Float32 | Already configurable via `ModbusByteOrder.WordSwap`; default per device profile | `DL205_Int32_word_order_is_CDAB` |
|
||
| **BCD-as-default** numeric storage (only IEEE 754 when ladder uses `R` type) | New decoder mode — register reads as `0x1234` for ladder value `1234`, not as decimal `4660` | `DL205_BCD_register_decodes_as_hex_nibbles` |
|
||
| **FC16 capped at 100 registers** (below the spec's 123) | Bulk-write batching must cap per-device-family | `DL205_FC16_101_registers_returns_IllegalDataValue` |
|
||
| **FC03/04 capped at 128** (above the spec's 125) | Less impactful — clients that respect the spec's 125 stay safe | `DL205_FC03_129_registers_returns_IllegalDataValue` |
|
||
| **V-memory octal-to-decimal addressing** (V2000 octal → 0x0400 decimal) | New address-format helper in profile config so operators can write `V2000` instead of computing `1024` themselves | `DL205_Vmem_V2000_maps_to_PDU_0x0400` |
|
||
| **C-relay → coil 3072 / Y-output → coil 2048** offsets | Hard-coded constants in DL205 device profile | `DL205_C0_maps_to_coil_3072`, `DL205_Y0_maps_to_coil_2048` |
|
||
| **Register 0 is valid** (rejects-register-0 rumour was DL05/DL06 relative-mode artefact) | None — current default is safe | `DL205_FC03_register_0_returns_V0_contents` |
|
||
| **Max 4 simultaneous TCP clients** on H2-ECOM100 | Connect-time: handle TCP-accept failure with a clearer error message | `DL205_5th_TCP_connection_refused` |
|
||
| **No TCP keepalive** | Driver-side periodic-probe (already wired via `IHostConnectivityProbe`) | _Covered by existing `ModbusProbeTests`_ |
|
||
| **No mid-stream resync on malformed MBAP** | Already covered — single-flight + reconnect-on-error | _Covered by existing `ModbusDriverTests`_ |
|
||
| **Write-protect exception code: `02` newer / `04` older** | Translate either to `BadNotWritable` | `DL205_FC06_in_ProgramMode_returns_ServerFailure` |
|
||
|
||
_Operator-reported / unconfirmed_ — covered defensively in the driver but no
|
||
integration tests until reproduced on hardware:
|
||
- TxId drop under load (forum rumour; not reproduced).
|
||
- Pre-2004 firmware ABCD word order (every shipped DL205/DL260 since 2004 is CDAB).
|
||
|
||
### Siemens SIMATIC S7
|
||
|
||
Quirk catalog at [`s7.md`](s7.md) — covers S7-1200 / S7-1500 / S7-300 / S7-400 /
|
||
ET 200SP. Modbus TCP isn't native; each platform exposes it via a different
|
||
add-on module with its own register-mapping conventions.
|
||
|
||
### Mitsubishi MELSEC
|
||
|
||
Quirk catalog at [`mitsubishi.md`](mitsubishi.md) — Modbus TCP via add-on modules
|
||
across the MELSEC family.
|
||
|
||
### Future devices
|
||
|
||
One section per device class, same shape as DL205. Quirks that apply across
|
||
multiple devices (e.g., "all AB PLCs use CDAB") can be noted in the cross-device
|
||
patterns section below once we have enough data points.
|
||
|
||
## Cross-device patterns
|
||
|
||
Once multiple device catalogs accumulate, quirks that recur across two or more
|
||
vendors get promoted into driver defaults or opt-in options:
|
||
|
||
- _(empty — filled in as catalogs grow)_
|
||
|
||
## Test conventions
|
||
|
||
- **One named test per quirk.** `DL205_word_order_is_CDAB_for_Float32` is easier to
|
||
diagnose on failure than a generic `Float32_roundtrip`. The `DL205_` prefix makes
|
||
filtering by device class trivial (`--filter "DisplayName~DL205"`).
|
||
- **Skip with a clear SkipReason.** Follow the pattern from
|
||
`GalaxyRepositoryLiveSmokeTests`: check reachability in the fixture, capture
|
||
a `SkipReason` string, and have each test call `Assert.Skip(SkipReason)` when
|
||
it's set. Don't throw — skipped tests read cleanly in CI logs.
|
||
- **Use the real `ModbusTcpTransport`.** Integration tests exercise the wire
|
||
protocol end-to-end. The in-memory `FakeTransport` from the unit test suite is
|
||
deliberately not used here — its value is speed + determinism, which doesn't
|
||
help reproduce device-specific issues.
|
||
- **Don't depend on simulator state between tests.** Each test resets the
|
||
simulator's register bank or uses a unique address range. Avoid relying on
|
||
"previous test left value at register 10" setups that flake when tests run in
|
||
parallel or re-order. Either the test mutates the scratch ranges and restores
|
||
on finally, or it uses pymodbus's REST API to reset state between facts.
|
||
|
||
## Next concrete PRs
|
||
|
||
- **PR 30 — Integration test project + DL205 profile scaffold** — **DONE**.
|
||
Shipped `tests/ZB.MOM.WW.OtOpcUa.Driver.Modbus.IntegrationTests` with
|
||
`ModbusSimulatorFixture` (TCP-probe, skips with a clear `SkipReason` when the
|
||
endpoint is unreachable), `DL205/DL205Profile.cs` (tag map stub), and
|
||
`DL205/DL205SmokeTests.cs` (write-then-read round-trip).
|
||
- **PR 41 — DL205 quirk catalog doc** — **DONE**. `docs/v2/dl205.md`
|
||
documents every DL205/DL260 Modbus divergence with primary-source citations.
|
||
- **PR 42 — ModbusPal `.xmpp` profiles** — **SUPERSEDED by PR 43**. Replaced
|
||
with pymodbus JSON because ModbusPal 1.6b is abandoned, GUI-only, and only
|
||
exposes 2 of the 4 standard tables.
|
||
- **PR 43 — pymodbus JSON profiles** — **DONE**. Dockerized under
|
||
`Docker/profiles/` (standard.json, dl205.json, mitsubishi.json,
|
||
s7_1500.json); compose file launches each via a named profile.
|
||
All bind TCP 5020.
|
||
- **PR 44+**: one PR per confirmed DL205 quirk, landing the named test + any
|
||
driver-side adjustment (string byte order, BCD decoder, V-memory address
|
||
helper, FC16 cap-per-device-family) needed to pass it. Each quirk's value
|
||
is already pre-encoded in `Docker/profiles/dl205.json`.
|