CanKit.Pro.J1939 1.2.3

CanKit.Pro.J1939

Application-layer SAE J1939 node for CanKit.Pro, covering SRS FR-J1939-001..006 (Must) and FR-J1939-007 (Should).

What it does

• PGN send/receive with 29-bit Priority / PF / PS / SA encoding & decoding via CanKit.Pro.Addressing.J1939Id (FR-J1939-001).
• SPN extraction from PGN payloads with configurable resolution and offset (little-endian, 1..64-bit fields) via J1939Spn (FR-J1939-002).
• Address claiming (PGN 0xEE00) with SAE J1939-81 §4.4.3 NAME arbitration and the 250 ms announcement window (FR-J1939-003).
• Address-Claim fallback (FR-J1939-004): after losing the preferred address to a higher-priority NAME the node scans the arbitrary address field (0x80..0xF7, wrapping once) and only broadcasts Cannot Claim (PGN 0xEE00 from SA = 0xFE) when the field is exhausted. Governed by J1939NodeOptions.EnableArbitraryAddressClaiming (default: derived from the NAME's Arbitrary Address Capable bit).
• Request-PGN (PGN 0xEA00) send and receive (FR-J1939-005).
• Auto-routing to J1939-TP for payloads > 8 bytes; direct 29-bit frames for payloads ≤ 8 bytes (FR-J1939-006).
• Periodic PGN send (FR-J1939-007): every periodic PGN — single- frame and multi-frame alike — is emitted on a fixed-rate grid anchored on the L2 DeadlineScheduler (t0 + n × period), so the long-run rate does not drift by the per-emission send time; ticks whose previous emission is still in flight are skipped and ticks that fell behind are coalesced. The schedule snapshots the caller's payload into an owned buffer at Start-time and hands SendAsync the same immutable bytes on every tick, so in-place edits to the caller buffer after StartPeriodicSend are not observable on the wire. SendAsync's pre-flight claim gate runs on every emission, so the schedule stops putting frames on the wire as soon as the node leaves Claimed and resumes automatically after a fresh claim — the emitted 29-bit ID is composed from the currently-claimed SA. Send failures (including J1939NoAddressException from the claim gate) are surfaced via BackgroundExceptionOccurred. The caller supplies the transmit period; mapping application PGNs to their SAE J1939-71 standard rate is the caller's responsibility (no PGN rate catalog is embedded). A native L1 IPeriodicTx optimization for single-frame PGNs remains a follow-up — its L1 error-propagation blocker is resolved (IPeriodicTx.Faulted).

Architecture

• Composes strictly on L2 (CanKit.Pro.RawCan.ICanBusService, CanKit.Pro.Actor.IProtocolActor, CanKit.Pro.Reliability.DeadlineScheduler) — no vendor SDK dependency.
• Uses CanKit.Pro.Addressing helpers (J1939Id, J1939Pgn, J1939Fields, J1939Name); the node never reimplements ID / PGN / NAME math.
• Delegates multi-frame transport to CanKit.Pro.J1939Tp per FR-J1939-006.
• Follows the same factory / interface / impl pattern as CanKit.Pro.Uds and CanKit.Pro.J1939Tp.

Usage

var options = new J1939NodeOptions(
    new J1939Name(
        identityNumber: 0x12345,
        manufacturerCode: 0x0AB,
        ecuInstance: 0, functionInstance: 0, function: 0x81,
        reserved: false,
        vehicleSystem: 0, vehicleSystemInstance: 0,
        industryGroup: 0, arbitraryAddressCapable: false));

using var bus = CanBus.Open("virtual://demo/0", cfg => cfg.SetProtocolMode(CanProtocolMode.Can20));
using var node = J1939Node.Open(bus, options);

await node.ClaimAddressAsync(preferredAddress: 0x11);

// Direct single-frame PGN (≤ 8 bytes).
await node.SendAsync(new J1939Message(pgn: 0xFEF0, payload: new byte[] { 1, 2, 3, 4 }));

// Multi-frame PGN (> 8 bytes) auto-routes through J1939-TP.
await node.SendAsync(new J1939Message(pgn: 0xFECA, payload: new byte[64]));

// Request-PGN.
await node.RequestPgnAsync(requestedPgn: 0xFEF1, destinationAddress: 0xFF);

// SPN extraction (little-endian, physical = raw * resolution + offset).
node.MessageReceived += (_, msg) =>
{
    double speed = J1939Spn.Extract(msg.Payload.Span,
        byteOffset: 3, startBit: 0, bitLength: 16,
        resolution: 0.125, offset: 0.0);
};

Status

Published on nuget.org since 1.2.0.

Install

dotnet add package CanKit.Pro.J1939

# plus a CanKit adapter for the hardware you actually talk to, e.g.
dotnet add package CanKit.Adapter.Virtual   # loopback, no hardware

Dependencies: CanKit.Abstractions, CanKit.Pro.Actor, CanKit.Pro.Addressing, CanKit.Pro.J1939Tp, CanKit.Pro.RawCan, CanKit.Pro.Reliability.

Part of CanKit.Pro — higher CAN protocol layers built on top of CanKit, which is consumed as a NuGet package rather than forked.

License

MIT — see LICENSE. CanKit itself is a separate project licensed under Apache-2.0; see THIRD-PARTY-NOTICES.md.