ApplyScaling (HistorianTagDefinition.ApplyScaling):
The EnsT2 trailer's second byte controls server-side scaling — `FE 00`
mirrors MinRaw to MinEU and sets AnalogTag.Scaling=0; `FE 01` persists
distinct MinRaw/MaxRaw and sets Scaling=1. Decoded by toggling
set_ApplyScaling on the native harness and capturing the wire bytes for
both values with identical inputs. The earlier docs claimed
EnsureTagAsync needed a follow-up "UpdateTags" call; the WCF surface has
no such operation — toggling that one byte is the whole fix.
StorageRate (HistorianTagDefinition.StorageRateMs):
Serializer accepts a non-default rate, validated empirically against
the live server which only accepts quantized values
(1000/5000/10000/60000/300000 ms).
EnsureTagAsync upsert semantics:
Second call on the same tag name with different fields succeeds and
updates Description, MinEU, MaxEU, MinRaw, MaxRaw, Scaling in place
(verified by direct SQL inspection in a live test).
Plan + doc closeout:
write-commands-reverse-engineering.md rewritten as a current-state
plan with three workstreams (A doc closeout / B idempotency / C1
StorageRate) and a parallelism table; prior phase notes preserved as
appendix. handoff.md, implementation-status.md, wcf-contract-evidence.md,
README.md updated to remove "writes are out of scope" / non-existent
UpdateTags references and document the actual EnsT2 wire format
including the `FE xx` trailer.
Reverse-engineering harness gains --write-apply-scaling and a SQL
post-check that prints the persisted AnalogTag bounds so future RE
sessions can verify wire→DB causality without leaving the harness.
169/169 tests pass (was 165; +4 new tests covering ApplyScaling,
StorageRate golden bytes, StorageRate live persistence, and
EnsureTagAsync upsert semantics).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Joseph Doherty
5ce62a5900