ModelingEvolution.CanOpen

Layer-1 CANopen protocol client over Linux SocketCAN — the CANopen analog of ModelingEvolution.Modbus. Pure protocol: no device or vendor vocabulary. It is the foundation for CANopen device adapters (e.g. the Fronius TPS 4000 welder — Epic 036).

Status: seeded from the bench-proven FroniusCanbus integration (validated against a real Beckhoff BK5120 + Fronius TPS 4000 on a Jetson reServer, 2026-06-02). Version 0.1.0 — preview.

Layer model

Layer 0  SocketCANSharp            raw CAN 2.0 frames (this package depends on it)
Layer 1  ModelingEvolution.CanOpen ← this package: NMT, SDO, PDO, object-dictionary addressing
Layer 2  ModelingEvolution.CanOpen.TaggedDevice   (future) named-tag device
Layer 3  vendor adapters           (e.g. FroniusWeldingMachine_TPS4000)

See docs/epics/cross-cutting/canopen-layers.md in the project-management repo.

What's in the box

• CanInterface — SocketCAN bring-up (ip link bitrate + optional GPIO terminator), thread-safe send, timed receive. Linux-only, requires root for bring-up.
• CanOpenClient — one background receive loop demultiplexing by COB-ID:
  • NMT — NmtStart(), NmtPreOperational(), Nmt(cmd)
  • SDO — expedited SdoUploadAsync / SdoDownloadAsync (+ sync SdoUpload)
  • TxPDO — Observe<T>(ObjectAddress, onValue) routes via the device's PDO mapping (read once from 0x1A00..0x1A03), or falls back to periodic SDO poll
  • RxPDO — Rx(cobId, dlc, period) returns a cyclic RxImage re-transmitted every period (the watchdog feed); mutate bits/bytes, the client sends snapshots
  • events BootupReceived, EmcyReceived
• ObjectAddress — (Index, Sub) object-dictionary address.
• Sdo — pure (de)serialization of expedited SDO frames (unit-testable, no I/O).
• PdoMap — decoded TxPDO mapping.

Quick example

using ModelingEvolution.CanOpen;

CanInterface.BringUp("can0", 500_000, terminatorGpio: "gpiochip2:8"); // host/root; skip if up already
using var bus = CanInterface.Open("can0");
using var co = new CanOpenClient(bus, nodeId: 5);
co.Start();

co.NmtStart();                                            // -> Operational
co.Observe<ushort>(new ObjectAddress(0x6401, 2),          // welding current actual (TxPDO2)
    raw => Console.WriteLine($"I = {raw / 65.535f:F0} A"));

var rx1 = co.Rx(CanOpenDefs.RxPdo(5, 1), dlc: 4, TimeSpan.FromMilliseconds(100)); // cyclic control
rx1.SetBit(0, 1, true);                                   // Robot-ready (held; watchdog fed @100ms)

Platform

Linux only (SocketCAN). Validated on ARM64 (Jetson) and x64. Bring-up needs root (ip link, gpioset); in containers prefer bringing can0 up on the host and only opening the socket here.

Releasing

Per org convention: never publish locally. Push a branch → CI publishes a preview (X.Y.Z-<branch>-<sha>); release.sh / a v* tag → CI publishes the stable release.