v0.2.0

Release v0.2.0

Date: 2026-03-12
Previous release: v0.1.0

Summary

Add minimal, transport-level SunSpec discovery APIs so callers can detect SunSpec devices, discover the SunSpec map base address, and enumerate SunSpec model headers (not full model metadata: no point decoding, names, or schema) without external SunSpec JSON or schema. These APIs are read-only discovery helpers and do not modify device state. Intended for device fingerprinting, protocol detection, and as a foundation for higher-level SunSpec libraries.

Default probe addresses are the official protocol candidates 0, 40000, 50000, plus adjacent compatibility offsets (1, 39999, 40001, 49999, 50001) to tolerate 0-based vs 1-based addressing confusion found in vendor documentation and tooling. Reaching MaxModels stops enumeration and returns the models collected so far without error (normal truncation).

Changes

Added

• SunSpec discovery (client)
  • DetectSunSpec(ctx, opts) — Probes candidate base addresses for the "SunS" marker; returns a structured result. "Not SunSpec" is not an error (Detected: false, error == nil). Uses the same request path as other client methods (lock per read, retries, metrics).
  • ReadSunSpecModelHeaders(ctx, opts, baseAddress) — Walks the model chain from baseAddress+2, returning model ID, length, and address ranges. Stops at end model (0xFFFF/0) or when guards trigger. Reaching MaxModels returns collected models without error. Malformed or non-progressing chains return partial results plus ErrSunSpecModelChainInvalid; exceeding MaxAddressSpan returns ErrSunSpecModelChainLimitExceeded. Invalid options (UnitID, RegType, empty BaseAddresses) return ErrUnexpectedParameters.
  • DiscoverSunSpec(ctx, opts) — Convenience: runs detection then model-header enumeration; returns combined result. Includes partial model results when the chain read fails partway.
• Types: SunSpecOptions, SunSpecProbeAttempt, SunSpecDetectionResult, SunSpecModelHeader, SunSpecDiscoveryResult.
• Sentinels: ErrSunSpecModelChainInvalid, ErrSunSpecModelChainLimitExceeded.
• UnitID zero defaults to 1 for scanner ergonomics (documented tradeoff).
• FC03/FC04 convenience read helpers — Generic read helpers usable for SunSpec and other fixed-field protocols (no SunSpec-specific logic):
  • ReadUint16Pair — Exactly two registers as [2]uint16.
  • ReadAsciiFixed — Same ASCII layout as ReadAscii but trailing spaces preserved.
  • ReadUint8s — Raw bytes in wire order (no SetEncoding).
  • ReadIPAddr — 4 bytes as IPv4 net.IP.
  • ReadIPv6Addr — 16 bytes as IPv6 net.IP.
  • ReadEUI48 — 6 bytes as MAC/EUI-48 net.HardwareAddr.
    Address and byte helpers use raw wire order and are unaffected by SetEncoding.

Unchanged

• No point decoding, scale factors, or schema-driven parsing; no JSON model definitions. SunSpec semantics remain the responsibility of a separate SunSpec library.