AB CIP @tags walker � CIP Symbol Object decoder + LibplctagTagEnumerator #130

dohertj2 · 2026-04-19T21:15:13-04:00

dohertj2 commented

2026-04-19 21:15:13 -04:00

Closes task #178. Real @tags walker replaces the EmptyAbCipTagEnumerator stub from PR 5. Pure-managed CipSymbolObjectDecoder parses the Symbol Object blob (Rockwell CIP Vol 1 layout � u32 instance-id + u16 type + u16 elem-len + 3�u32 dims + u16 name-len + name + pad); 12 atomic type codes + struct/system flags. LibplctagTagEnumerator reads @tags via libplctag Tag.GetBuffer + hands bytes to the decoder. EnableControllerBrowse option (default false) gates the walk. 26 new tests, 192/192 passing. Merges to v2.

dohertj2 added 1 commit 2026-04-19 21:15:15 -04:00

AB CIP @tags walker — CIP Symbol Object decoder + LibplctagTagEnumerator. Closes task #178 . CipSymbolObjectDecoder (pure-managed, no libplctag dep) parses the raw Symbol Object (class 0x6B) blob returned by reading the @tags pseudo-tag into an enumerable sequence of AbCipDiscoveredTag records. Entry layout per Rockwell CIP Vol 1 + Logix 5000 CIP Programming Manual 1756-PM019, cross-checked against libplctag's ab/cip.c handle_listed_tags_reply — u32 instance-id + u16 symbol-type + u16 element-length + 3×u32 array-dims + u16 name-length + name[len] + even-pad. Symbol-type lower 12 bits carry the CIP type code (0xC1 BOOL, 0xC2 SINT, …, 0xD0 STRING), bit 12 is the system-tag flag, bit 15 is the struct flag (when set lower 12 bits become the template instance id). Truncated tails stop decoding gracefully — caller keeps whatever parsed cleanly rather than getting an exception mid-walk. Program:-scope names (Program:MainProgram.StepIndex) are split via SplitProgramScope so the enumerator surfaces scope + simple name separately. 12 atomic type codes mapped (BOOL/SINT/INT/DINT/LINT/USINT/UINT/UDINT/ULINT/REAL/LREAL/STRING + DT/DATE_AND_TIME under Dt); unknown codes return null so the caller treats them as opaque Structure. LibplctagTagEnumerator is the real production walker — creates a libplctag Tag with name=@tags against the device's gateway/port/path, InitializeAsync + ReadAsync + GetBuffer, hands bytes to the decoder. Factory LibplctagTagEnumeratorFactory replaces EmptyAbCipTagEnumeratorFactory as the AbCipDriver default. AbCipDriverOptions gains EnableControllerBrowse (default false) matching the TwinCAT pattern — keeps the strict-config path for deployments where only declared tags should appear. When true, DiscoverAsync walks each device's @tags + emits surviving symbols under Discovered/ sub-folder. System-tag filter (AbCipSystemTagFilter shipped in PR 5) runs alongside the wire-layer system-flag hint. Tests — 18 new CipSymbolObjectDecoderTests with crafted byte arrays matching the documented layout — single-entry DInt, theory across 12 atomic type codes, unknown→null, struct flag override, system flag surface, Program:-scope split, multi-entry wire-order with even-pad, truncated-buffer graceful stop, empty buffer, SplitProgramScope theory across 6 shapes. 4 pre-existing AbCipDriverDiscoveryTests that tested controller-enumeration behavior updated with EnableControllerBrowse=true so they continue exercising the walker path (behavior unchanged from their perspective). Total AbCip unit tests now 192/192 passing (+26 from the RMW merge's 166); full solution builds 0 errors; other drivers untouched. Field validation note — the decoder layout matches published Rockwell docs + libplctag C source, but actual @tags responses vary slightly by controller firmware (some ship an older entry format with u16 array dims instead of u32). Any layout drift surfaces as gibberish names in the Discovered/ folder; field testing will flag that for a decoder patch if it occurs. 088c4817fe

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

dohertj2 merged commit b55cef5f8b into v2

2026-04-19 21:15:18 -04:00

dohertj2 referenced this issue from a commit

2026-04-19 21:15:19 -04:00

Merge pull request (#130) - AbCip @tags walker

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Reference: dohertj2/lmxopcua#130