BMS: identify DIDs for iBMS bootstrap-only fields (Device list/info, DI/SW/Relay/Hall) #27

The iBMS PC Utility's periodic poll set is exactly 33 DIDs and our util/capture_dual_can.py / bms/solectrac-bms-diagnostics.py already match it 1:1 (audited against dual-capture-charging-120-10p-to-100p.asc). However, the History → XLSX export surfaces fields that aren't reachable from any DID we currently poll — they must come from one-shot reads at the bootstrap / connection phase, not from steady-state polling.

Fields the XLSX exposes that we don't have a DID for

From the 2026-06-13/14 XLSX historical exports (2290432064100800D090A000A0000022_*.xlsx):

UDAN tag 0x92 Device info (11 cols):

• releaseName = A650_C121.074.001.01_T1.0.2 (firmware identifier)
• SCID = 40-char hex (SHA-1?)
• Custom info. ver., FW zone
• Up time, Current mode
• Charging cycles (= 0, broken/unused on this BMS — actual cycle count is elsewhere)
• FWID, BurnID (manufacturer codes)
• PackSN (unpopulated on this pack but the column exists)

UDAN tag 0x82 Device list (7 cols):

• VIN (placeholder 1234567890ABCDEF on this tractor)
• Hardware Device count, per-device HWID + FWVersion
• Device 1 HWID = 2290432064100800D090A000A0000022 (matches export filename — global BMS identifier)

System state 0x93 fields we don't surface (subset; many are from currently-polled DIDs but others aren't):

• DI1 / DI2 (discrete inputs — could anchor key / seat / brake state)
• SW1 / SW2 (switch inputs)
• Relay 0 / Relay 1 (Close / Open vendor-labeled relay states) + Relay count
• HALL Power Supply Voltage (mV) (= 0 on this pack, but useful as a sanity-check anchor)
• HALL Channel 1/2 Calibration Current (A)
• Reset source (= Powered On always in this export)
• Slave communication interruption status

Proposed approach

1. Record an iBMS bootstrap-only capture — start a CAN trace on the diagnostic bus, then connect iBMS PC Utility, let it complete the connect/identity phase, then disconnect. Should be ~10–30 s.
2. Extract all UDS 22 XX YY requests the iBMS sends during bootstrap (separate from the steady-state poll set we already mirror). Diff against our ALL_POLLS.
3. Map each bootstrap DID to the field it populates by looking at the iBMS UI tab that displays the value (System overview / Device info / etc.).
4. Add a --bootstrap-only mode to util/capture_dual_can.py (or extend bms/solectrac-bms-diagnostics.py:read_identity) to read those DIDs once at startup and surface the values.

Not blocking on this

The DIDs we already poll cover all the high-value live state (pack V/A/SOC, alarms, charging telemetry, peak data, balancing). The fields above are nice-to-have inventory / identity / discrete-IO additions, not critical for live monitoring. Worth picking up next time the iBMS is being connected to the tractor anyway — opportunistic capture.

See bms/README.md §"Polling patterns" for the current 33-DID inventory and bms/solectrac-bms-diagnostics.py ALL_POLLS for the code list.