The read translation R6:0.DN -> R6:0.CON/13 made those names parse in libplctag, which
would have turned a write - previously impossible, tag creation failed - into a masked
write to the control word. LibplctagLegacyTagRuntime.WriteRefusal (via
IAbLegacyTagFactory.WriteRefusal, same plumbing as native) now refuses writes to every
rewritten status bit (R EN/EU/DN/EM/ER/UL/IN/FD, C UA) with BadNotSupported before a
runtime is created; the runtime also refuses as defence in depth. Reads stay
translated. T/C status bits libplctag parses itself keep their pre-existing behaviour.
13 new tests fail with the predicate disabled.
Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
Joseph Doherty
7dbb060f92