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Mark corrections-doc C1 (driver list pre-survey) as RESOLVED — the OtOpcUa team has confirmed all seven v2 drivers (Modbus TCP including DL205, AB CIP, AB Legacy, S7, TwinCAT, FOCAS, OPC UA Client) plus Galaxy/MXAccess by direct knowledge of the equipment estate; the survey is no longer a v2 prerequisite. TwinCAT and AB Legacy specifically called out as committed by known Beckhoff and SLC/MicroLogix legacy installations. Survey may still inform long-tail driver scoping and per-site capacity planning per the handoff's Long-tail drivers section, but the v2 driver list is fixed. Recommends the handoff's "Core library scope is driven by the survey" wording be updated to reflect that the v2.0 core library is pre-committed by direct equipment-estate knowledge, with the survey informing only long-tail driver scoping. Captured as lmxopcua decision #128 (2026-04-17).

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Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Joseph Doherty
2026-04-17 11:35:34 -04:00
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handoffs/otopcua-corrections-2026-04-17.md
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@@ -113,31 +113,16 @@ For the Warsaw campuses with one cluster per building, a consumer that needs vis
## C. Architectural decisions to revisit
### C1. Driver list committed for v2 implementation before Equipment Protocol Survey results
### C1. Driver list committed for v2 implementation before Equipment Protocol Survey results — **RESOLVED**
**Plan currently says** (handoff §"Driver Strategy"):
> **Core library scope is driven by the equipment protocol survey** — see below and `../current-state/equipment-protocol-survey.md`. A protocol becomes "core" if it meets any of: Present at 3+ sites; Combined instance count above ~25; Needed to onboard a Year 1 or Year 2 site; Strategic vendor whose equipment is expected to grow.
And: "It has not been run yet."
**Resolution** (lmxopcua decision #128, 2026-04-17): the seven committed drivers (Modbus TCP including DL205, AB CIP, AB Legacy, S7, TwinCAT, FOCAS, OPC UA Client) plus the existing Galaxy/MXAccess driver are confirmed by direct knowledge of the equipment estate, **not pending the formal survey**. TwinCAT and AB Legacy were specifically confirmed as committed v2 drivers by the OtOpcUa team based on known Beckhoff installations and known SLC/MicroLogix legacy equipment in the estate.
**What was found:** The v2 design (`lmxopcua/docs/v2/driver-specs.md`) commits to seven specific drivers in addition to Galaxy:
1. Modbus TCP (also covers DL205 via octal address translation)
2. AB CIP (ControlLogix / CompactLogix)
3. AB Legacy (SLC 500 / MicroLogix, PCCC) — separate driver from CIP
4. S7 (Siemens S7-300/400/1200/1500)
5. TwinCAT (Beckhoff ADS, native subscriptions)
6. FOCAS (FANUC CNC)
7. OPC UA Client (gateway for OPC UA-native equipment)
The Equipment Protocol Survey may still produce useful inventory data for downstream planning (per-site capacity sizing, prioritization order between drivers, on-demand long-tail driver scoping per the handoff's "Long-tail drivers" section), but **adding or removing drivers from the v2 implementation list is out of scope for the survey**. The v2 driver list is fixed.
This commitment was made before the survey ran. The handoff's pre-seeded categories (EQP-001 through EQP-006) confirm OPC UA-native, S7, AB, Modbus, FANUC CNC as expected. **TwinCAT (Beckhoff ADS)** is not in the handoff's expected list, and **AB Legacy as separate from AB CIP** is a finer split than the handoff anticipated.
**Plan should say instead:** Either:
- (a) The plan should acknowledge that the OtOpcUa team has internal knowledge confirming TwinCAT and AB Legacy as committed core drivers ahead of the formal survey (e.g. known Beckhoff installations at specific sites, known SLC/MicroLogix legacy equipment).
- (b) The v2 design should defer the TwinCAT and AB Legacy commitments until the survey runs in Year 1 Q1 — implementation order becomes Modbus → AB CIP → S7 → FOCAS → (survey results) → potentially add TwinCAT, AB Legacy.
Note: from a purely technical standpoint, AB CIP and AB Legacy share the libplctag library, so the marginal cost of adding AB Legacy to the AB CIP driver work is low. But it's still a separate driver instance with its own stability tier (B), test coverage, and Admin UI surface.
**Recommendation:** option (a) — confirm the pre-commitment is justified by known site equipment, document the justification, and proceed. Re-evaluate after the survey if any of these protocols turn out to be absent from the estate.
**Plan should say instead:** the handoff's "Core library scope is driven by the survey" wording should be updated to reflect that the v2.0 core library is **pre-committed** by direct equipment-estate knowledge, with the survey informing only long-tail driver scoping and per-site planning details.
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