- L2: WriteWidthRefusal leaves a BOOL over a wider value to a runtime that sees the CIP
type (native): mistyped integer member -> BadTypeMismatch (as its read), 0xD3 BOOL-array
DWORD -> BadNotSupported; libplctag keeps BadNotSupported for both (size only).
- L4: direct theory over WriteWidthRefusal (1/2/4/8 widths incl LINT/ULINT/LREAL, String/Dt,
unknown size) + array/bit-selector exemptions with a non-vacuous control.
- L1: CLAUDE.md member/BIT-member writes are ab_server-proven only.
- L3: patch 0003 blind spots documented (Docker README, AbServer-Test-Fixture.md); nits.
Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
Item 2 — controller-discovered UDT members are writable on both transports once
browse-committed and authored ReadWrite (writability is the operator's: the commit
lands AccessLevel Read with no writable key). The write names the member (one CIP
symbolic segment per member), its own type, its own bytes. BIT members are supported:
Z-35162 (read-only probe) exposes a UDT BIT member as a 1-byte 0xC1 BOOL, so the
controller applies the bit and the hidden host's other bits are never in the request.
- AbCipDriver: pre-write width check on BOTH transports (libplctag patched part of
its read buffer and sent it all): BadTypeMismatch, Bool over a wider value
BadNotSupported; nothing sent, handle kept, health untouched, warn once.
- A runtime NotSupportedException is a refusal: no longer latches Degraded.
Item 3 — whole-UDT writes refused BadNotSupported before any runtime exists, by
decision (a structure write overwrites hidden hosts + padding), documented.
ab_server patch 0003: serve member paths from dotted flat tags (UdtSeg.*), and
accept libplctag's pad byte on 1-byte writes (stock ab_server refused every
libplctag BOOL/SINT write with 0x03). New AbCipUdtMemberWriteTests (both
transports), AbCipDiscoveredMemberWriteTests, native request-byte theory, and a
browse-commit mapper pin. Docs: AbCip.md Member writes / Whole-UDT writes / Known
gaps, fixture docs, CLAUDE.md AB section.
Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
Joseph Doherty