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
5018627b35