In T21 press pass 1, two REAL tags diverged only because their live values moved
between the sequential libplctag and native phases (WW_M4ActualTemp 384.887 ->
385.138).
The libplctag phase now reads every selected tag a second time, paced, before
native starts (TransportObservations.ProbeReads). A tag whose two libplctag reads
both succeed and differ is classed live. For a live tag, parity still requires:
- the same status (and the native-TypeMismatch rule);
- no decode error;
- the same raw length;
- the same CIP type code when both sides expose one (native records it now;
libplctag.NET 1.5.2 does not);
- the same decoded shape.
Value equality is not required. Live tags get their own list and a "libplctag
probe" table column, and are counted as neither expected nor unexpected
divergences.
A tag that reads stable on libplctag but differs on native is still an unexpected
divergence, and a missing or failed probe never makes a tag live. The offline pin
A_live_value_is_compared_structurally_and_a_stable_one_by_value goes red with the
live branch disabled.
Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
Joseph Doherty
82a0c298ce