Review r0 M9. The AdminUI form wrote coalesceReads:true on every save, pinning
today's default into every edited driver. AbLegacyDriverOptions.CoalesceReads
is now bool? (null = default ON, never serialised, same encoding as
Transport); the form omits the key when the switch is on and writes only an
explicit false. Persisted coalesceReads:true keeps loading as on.
Refs #738
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Review r0 I1. On the default libplctag transport a PLC refusal (non-zero PCCC
STS, e.g. an element past the end of the file; or a CIP error) arrives as
ERR_REMOTE_ERR / ERR_BAD_STATUS, which fell into the BadConnection default: a
no-reply comms fault. A coalesced block with one such member then failed as a
group every poll, and two refused tags in a row opened the device's fail-fast
window against a device that was answering.
- LibplctagLegacyStatusTranslation maps ERR_REMOTE_ERR / ERR_BAD_STATUS to the
existing AbStatus.DeviceStateConflict (BadDeviceFailure): "reachable, refused
the operation". No new AbStatus value (Driver.Ab.Transport is Lane K's).
- IsNoReply (Timeout / BadConnection / Abort / Pending / unknown codes) is now
the ONLY comms-fault class; IsDeviceRefusal is every other non-Ok status
except Unsupported (BadReply / Partial included: a reply arrived).
- A coalesced block refused with ANY returned status falls back to per-member
reads in the same pass; the shape is remembered only after a repeat, and the
refused block's handle is always evicted (M5).
- A runtime status Unsupported is neutral (keeps the handle); the probe no
longer counts it as a fault.
- Refusal warnings log the status actually answered (M8).
Live: the new past-end-of-file ab_server case fails on libplctag with the old
translation and passes with it, on slc500/micrologix/plc5 x both transports.
Refs #738
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Review 07 P7 (rest): adjacent words on one data file were never coalesced
(one round trip per tag) although the array path proves the transport can read
a span. Within a device pass, scalar tags on one N/B/F/L file within 8
elements of each other (block <= 200 data bytes, under the 236-byte typed-read
limit) now ride one multi-element read and are decoded from their offsets with
exactly the CLR types the single-tag path returns (int / float / bool).
Only shapes the single path decodes identically are coalesced: indirect,
sub-element, array, file-number-less (S:/I:/O:) and width-mismatched tags keep
the single path. A block the device refuses (an authored element past the end
of the file, a native PLC-5 non-N file) falls back to per-tag reads for its
members and its shape is remembered; a comms fault fails the members together.
New driver-config key coalesceReads (default true) with an AdminUI switch
(Razor change: AbLegacyDriverForm, for the Wave 4 live check). Adds an
env-gated ab_server parity case (coalesced == per-tag values).
Refs #738
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Joseph Doherty