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Joseph Doherty 366212417c Task #143 — Modbus block-read coalescing (with max-gap knob)

Adds a coalescing read planner that merges nearby tags into single FC03/FC04
PDUs, opt-in via ModbusDriverOptions.MaxReadGap. Default 0 = no coalescing
(every tag gets its own PDU — preserves pre-#143 wire output).

Worked example with MaxReadGap=10:
  T1 @ HR 100 (Int16, 1 reg)
  T2 @ HR 102 (Int16, 1 reg, gap 1 → joins block)
  T3 @ HR 110 (Float32, 2 regs, gap 7 → joins block)
  T4 @ HR 200 (Int16, 1 reg, gap 89 → splits, separate read)
  → 2 PDUs total: FC03 start=100 quantity=12 + FC03 start=200 quantity=1.

Planner:
- Eligible tags: known + register region (HR/IR) + scalar + not String /
  BitInRegister / array + not CoalesceProhibited.
- Groups by (UnitId, Region) — never coalesces across slaves or regions.
- Sorts by start address; merges when (next.start - last.end - 1) ≤ MaxReadGap
  AND the resulting span ≤ MaxRegistersPerRead. Otherwise opens a new block.
- Single-tag blocks are deferred to the per-tag path so WriteOnChange cache
  semantics stay correct without duplication.
- Per-block failure marks every member tag Bad and degrades health — same
  semantics the per-tag path has, but at the block granularity.

Per-tag escape hatch ModbusTagDefinition.CoalesceProhibited (bool, default
false) — when true, the tag is read in isolation regardless of MaxReadGap.
For PLCs with protected register holes between adjacent tags.

Tests (7 new ModbusCoalescingTests):
- MaxReadGap=0 keeps the per-tag behavior (2 reads for 2 tags).
- MaxReadGap=2 merges 3 tags within 5 registers into 1 read of qty=5.
- MaxReadGap=10 splits T1+T2 from T3 when the gap exceeds the threshold.
- CoalesceProhibited tag reads alone even when neighbours are eligible.
- Coalescing never crosses UnitId boundaries (multi-slave gateway safety).
- MaxRegistersPerRead caps a would-be block; planner falls back to separate
  reads when the merged span would exceed the cap.
- Per-tag values surface independently after coalescing (slice-math sanity).

Existing 220 unit tests still green; total 224 pass with the new file (tests
are additive, no regressions).

Follow-up: auto-split-on-protected-hole isn't shipped — a coalesced read
that hits an Illegal Data Address right now marks every member Bad until
the operator sets CoalesceProhibited on the offending tag. Tracked
implicitly by #138's e2e drill against a pymodbus profile with a protected
hole mid-block.

2026-04-25 00:21:18 -04:00

DirectLogicAddressTests.cs

Phase 3 PR 50 -- DL260 bit-memory address helpers (Y/C/X/SP) + live coil integration tests. Adds four new static helpers to DirectLogicAddress covering every discrete-memory bank on the DL260: YOutputToCoil (Y0=coil 2048), CRelayToCoil (C0=coil 3072), XInputToDiscrete (X0=DI 0), SpecialToDiscrete (SP0=DI 1024). Each helper takes the DirectLOGIC ladder-logic address (e.g. 'Y0', 'Y17', 'C1777') and adds the octal-decoded offset to the bank's Modbus base per the DL260 user manual's I/O-configuration chapter table. Uses the same 'octal-walk + reject 8/9' pattern as UserVMemoryToPdu so misaligned addresses fail loudly with a clear ArgumentException rather than silently hitting the wrong coil. Fixes a pymodbus-config bug surfaced during integration-test validation: dl205.json had bits entries at cell indices 2048 / 3072 / 4000, but pymodbus's ModbusSimulatorContext.validate divides bit addresses by 16 before indexing into the shared cell array -- so Modbus coil 2048 reads cell 128, not cell 2048. The sim was returning Illegal Data Address (exception 02) for every bit read in the Y/C/scratch range. Moved bits entries to cells 128 (Y bank marker = 0b101 for Y0=ON, Y1=OFF, Y2=ON), 192 (C bank marker = 0b101 for C0/C1/C2), 250 (scratch cell covering coils 4000..4015). write list updated to the correct cell addresses. Unit tests: YOutputToCoil theory sweep (Y0->2048, Y1->2049, Y7->2055, Y10->2056 octal-to-decimal, Y17->2063, Y777->2559 top of DL260 Y range), CRelayToCoil theory (C0->3072 through C1777->4095), XInputToDiscrete theory, SpecialToDiscrete theory (with case-insensitive 'SP' prefix). Bit_address_rejects_non_octal_digits (Y8/C9/X18), Bit_address_rejects_empty, accepts_lowercase_prefix, accepts_bare_octal_without_prefix. 48/48 Modbus.Tests pass. Integration tests: DL205CoilMappingTests with three facts -- DL260_Y0_maps_to_coil_2048 (FC01 at Y0 returns ON), DL260_C0_maps_to_coil_3072 (FC01 at C0 returns ON), DL260_scratch_Crelay_supports_write_then_read (FC05 write + FC01 read round-trip at coil 4000 proves the DL-mapped coil bank is fully read/write capable end-to-end). 9/9 DL205 integration tests pass against the pymodbus dl205 profile with MODBUS_SIM_PROFILE=dl205. Caller opts into the helpers per tag the same way as PR 47's V-memory helper -- pass DirectLogicAddress.YOutputToCoil("Y0") as the ModbusTagDefinition Address; no driver-wide DL-family flag. PR 51 adds the X-input read-side integration test (there's nothing to write since X-inputs are FC02 discrete inputs, read-only); PR 52 exception-code translation; PR 53 transport reconnect-on-drop since DL260 doesn't send TCP keepalives.

2026-04-18 22:22:42 -04:00

MelsecAddressTests.cs

Phase 3 PR 59 -- MelsecAddress helper for MELSEC X/Y hex-vs-octal family trap + D/M bank bases. Adds MelsecAddress static class with XInputToDiscrete, YOutputToCoil, MRelayToCoil, DRegisterToHolding helpers and a MelsecFamily enum {Q_L_iQR, F_iQF} that drives whether X/Y addresses are parsed as hex (Q-series convention) or octal (FX-series convention). This is the #1 MELSEC driver bug source per docs/v2/mitsubishi.md: the string 'X20' on a MELSEC-Q means DI 32 (hex 0x20) while the same string on an FX3U means DI 16 (octal 0o20). The helper forces the caller to name the family explicitly; no 'sensible default' because wrong defaults just move the bug. Key design decisions: (1) Family is an enum argument, not a helper-level static-selector, because real deployments have BOTH Q-series and FX-series PLCs on the same gateway -- one driver instance per device means family must be per-tag, not per-driver. (2) Bank base is a ushort argument defaulting to 0. Real QJ71MT91/LJ71MT91 assignment blocks commonly place X at DI 8192+, Y at coil 8192+, etc. to leave the low-address range for D-registers; the helper takes the site's configured base as runtime config rather than a compile-time constant. Matches the 'driver opt-in per tag' pattern DirectLogicAddress established for DL260. (3) M-relay and D-register are DECIMAL on every MELSEC family -- docs explicitly; the MELSEC confusion is only about X/Y, not about data registers or internal relays. Helpers reject non-numeric M/D addresses and honor bank bases the same way. (4) Parser walks digits manually for both hex and octal (instead of int.Parse with NumberStyles) so non-hex / non-octal characters give a clear ArgumentException with the offending char + family name. Prevents a subtle class of bugs where int.Parse('X20', Hex) silently returns 32 even for F_iQF callers. Unit tests (MelsecAddressTests, 34 facts): XInputToDiscrete_QLiQR_parses_hex theory (X0, X9, XA, XF, X10, X20, X1FF + lowercase); XInputToDiscrete_FiQF_parses_octal theory (X0, X7, X10, X20, X777); YOutputToCoil equivalents; Same_address_string_decodes_differently_between_families (the headline trap, X20 => 32 on Q vs 16 on FX); reject-non-octal / reject-non-hex / reject-empty / overflow facts; honors-bank-base for X and M and D. 176/176 Modbus.Tests pass (143 prior + 34 new Melsec). No driver core changes -- this is purely a new helper class in the Driver.Modbus project. PR 60 wires it into integration tests against the mitsubishi pymodbus profile.

2026-04-18 23:04:52 -04:00

ModbusArrayTests.cs

Task #137 — Modbus per-tag suffix grammar (type / bit / byte-order / array)

2026-04-24 23:49:22 -04:00

ModbusBitRmwTests.cs

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.