python-can-canpal

CANPAL USB and TCP client backend for python-can.

0.1.0rc2 is an experimental preview. Full hardware release acceptance is incomplete. Use it for evaluation on an isolated test bench. It is not the qualified 0.1.0 release.

Install

Requires Python 3.12, python-can 4.6.1, pySerial 3.5, and a separately supplied 64-bit CANPAL native SDK with the fixes described below.

python -m pip install python-can-canpal==0.1.0rc2

The Python package does not include the CANPAL SDK, firmware, device drivers, Qt/MinGW runtime, or fake binaries. Obtain compatible native components from your CANPAL supplier before attempting hardware access. The MIT license applies to the new Python plugin, tests and documentation; native components have separate licenses.

What has been verified

Both devices had CAN1 wired to their own CAN2 on separate physical buses. These checks do not use an independent reference CAN interface. Classic checks covered standard/extended frames and RTR DLC 0–8 in both directions. X6 FD checks covered lengths 0–64 and BRS off/on. The current SDK checks verified 19,680 frames and 20 Windows reopen cycles. Of these, 4,384 frames were verified on Linux USB using usbipd-win 5.3.0 and Linux CDC ACM. Reversing attachment order swapped ttyACM0/ttyACM1 while UID selection still found the correct X5 and X6.

SDK software regressions passed 170 assertions on each of Windows x64, Windows x86, and Ubuntu x86_64, plus two Linux ThreadSanitizer checks. Windows x86 SDK checks do not qualify a 32-bit Python plugin configuration.

Not yet qualified: independent-reference CAN/CAN FD interoperability, physical Linux host USB controllers, direct Linux WLAN, two simultaneous WLAN devices, full repeated physical renumbering/disconnection acceptance, rated-load/endurance runs, and native resource stability. Formal 0.1.0 retains the complete release acceptance requirements.

Native SDK and firmware requirements

Request CANPAL native SDK build 663eda8 from your CANPAL supplier through the existing supplier channel. Windows x64 and Ubuntu 24.04 x86_64 runtime bundles are supplied on request, separately from PyPI. Match the binary SHA256 below and the bundle manifest before use; updating this Python package alone does not update your installed native SDK.

The pinned source revision is 663eda823be0533754123695405033b38e115489. It adds stricter CAN ACK validation, TCP buffered-read handling, immediate OBD write-error propagation, UDS source filtering, and synchronized command handoff. It also includes cooperative worker shutdown and the Qt serial buffered-read fix. The firmware protocol has no transaction sequence, so a delayed ACK for an identical earlier request cannot be distinguished by the echoed fields alone.

Matching exported function names or the SDK version string alone does not identify this fixed build. rc2 updates the SDK baseline, validation tooling and documentation; its Python runtime behavior is unchanged from rc1.

Classic RTR also requires firmware that preserves the received DLC. The original X5 firmware reporting 0x0332 and X6 firmware reporting 0x0127 cleared RTR DLC to zero. Supplier-signed diagnostic builds fixed this on the two test devices. Those builds still report the same version numbers: ask your supplier to identify the actual fixed build. The plugin cannot recover DLC that firmware has discarded.

Set CANPAL_LIBRARY to the absolute DLL/SO path, or pass library_path. On Windows, CANPAL_DEPENDENCY_DIRS may list Qt/MinGW runtime directories, separated by semicolons. On Linux, install the matching Qt 5 runtime and grant serial-port access through udev or the dialout group.

Connect by UID or IP

import can

with can.Bus(interface="canpal", ignore_config=True,
             transport="usb", device_id="YOUR_24_HEX_DIGIT_UID",
             channel=0, bitrate=500_000) as bus:
    message = bus.recv(timeout=1)

The device UID remains the selector when a COM/ttyACM number changes. After a reconnection, close and recreate the Bus using the same UID; automatic reconnect is not implemented. A Linux USB/IP enumeration-order swap has been verified; the full repeated physical renumbering acceptance remains pending.

Use transport="wlan", host="192.0.2.10", port=8000 for TCP direct connection. The IP and port must match the actual device; no network discovery is attempted. Keep device_id to verify identity at that endpoint. X6 CAN FD additionally uses fd=True, data_bitrate=2_000_000.

Different physical devices use independent Bus objects. A device can have one Bus and one selected CAN channel at a time. Use one Notifier per device for independent fault handling. UDP, server mode, transmit echo and concurrent channels on one device are not implemented.

A successful send() means the native queue accepted the frame, not that the CAN bus acknowledged it. Use a single receiver per Bus, stop its Notifier before shutdown, and handle python-can exceptions. Timestamp alignment is approximate per device and does not provide precise synchronization between devices.

The source distribution includes Chinese installation, testing and release notes.