Read-only live gate on Elma presses Z35474 (TC3 3.1.4024) and Z34834 (TC2 2.11):
- Sum-read: every chunk came back BadCommunicationError. Beckhoff's
SumRead(IList<IgIoSumReadEntity>) ctor casts to IList<SumDataEntity>, which
throws InvalidCastException for a List<> (only an array survives via
covariance). The fake-client tests never built a real SumRead. New
AdsTwinCATClient.CreateSumRead passes an array; TwinCATSumReadConstructionTests
pins it (red on the List form) plus a falsifiability control on the library.
After the fix: 59 tags, status identical everywhere, values identical on every
non-moving tag, ~0.35-0.66 s vs ~2.7 s per poll; TC2 CE 2.11 answers sum reads.
- An unexpected sum chunk failure now logs one Warning per device (it was
invisible: the health message was overwritten by the next good read).
- Diagnostics: TC2 has no TwinCAT_SystemInfoVarList; fall back to .SYSTEMINFO /
.SYSTEMTASKINFOARR[1] once the TC3 name answers not-found (live: all six keys).
- #612 browse: Flat verified on TC3 (10,770 leaves; VirtualTree 1,459 strict
subset) — comment and docs updated, no load-mode option needed.
Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
Strict width+kind eligibility for sum-batched scalars (others read singly); latch only on ADS
1793/1794, split 1792/1797/1798 without latching; 32 KiB per-command budget and 500-item ceiling;
short sum response handled per item. Diagnostics: opt-in diagnosticsEnabled (default off), reuse the
probe's ReadState, sample after the host-state transition, JitterMs renamed HeadroomMs, compact
per-device line so many devices fit the 16-entry cap, unavailable-symbol latch cleared on reconnect.
AdminUI: min/max on sum-read max, diagnostics checkbox. Pure planner extracted and unit-tested.
Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
Sum-read (#310): batches a poll's reads per device into sum commands capped at sumReadMaxItems,
per-item ADS errors mapped per tag, falls back to individual reads when the target refuses the
command. Diagnostics (#314): ADS state, app name, online-change count, task cycle/exec/jitter via
IDriverDiagnostics. Re-implemented against the current raw-byte read path (stranded auto/driver-gaps
commits predate it). Sum-write not ported. Unit tests only; live gate pending a route.
Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
Joseph Doherty