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A CAN bus can replace a bulky bundle of toolhead signal wires with a remote toolboard connected over CANH and CANL, alongside power and ground. It is most useful when a moving toolhead, several remote boards or frequent toolhead changes make wiring difficult to manage. For a simple printer with one remote MCU, USB is usually easier to set up and may be all you need.
What CAN changes on a 3D printer
CAN is a multi-node bus: rather than wiring each toolhead peripheral back to a central controller, you can place a compatible toolboard near the toolhead and connect local peripherals there. The printer then carries power, ground and the CAN differential pair to that board. This makes the toolhead connection more modular and can reduce the number of separate signal wires in the moving cable bundle.
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The toolboard is still a microcontroller that needs compatible firmware and configuration. Klipper supports CAN on STM32, SAME5x and RP2040 microcontrollers when the board includes a CAN transceiver. A compatible host-side USB-to-CAN adapter is also needed unless you configure a supported MCU to act as a USB-to-CAN bridge. (Klipper documentation, “CANBUS”; FLY Docs, “CAN Network Configuration and ID Search”; EBB36/EBB42 v1.0 setup documentation.)
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CAN versus USB for a Klipper toolhead
| Consideration | USB | CAN |
|---|---|---|
| Moving cable bundle | A USB connection can be straightforward for one remote MCU, but the toolhead still needs its peripheral connections arranged. | A remote toolboard can handle local peripherals, with power and the CAN pair running to it. |
| Remote nodes and expansion | Usually a simpler fit for a single remote MCU. | Designed for multiple nodes on a bus; more attractive as the toolhead or node count grows. |
| Setup effort | Typically less setup for a single remote MCU. | Requires CAN firmware, Linux interface configuration, node discovery and bus wiring checks. |
| Physical bus requirements | No CAN termination requirement. | Requires two 120-ohm terminators at the physical ends of the bus. |
| Fault isolation | USB and CAN have different configuration and wiring failure modes; the relevant checks depend on the connection in use. | Bus state, bitrate consistency, node visibility and termination are useful checks before investigating motion-system problems. |
CAN is not automatically faster or better for every printer. Its practical advantage is the distributed wiring arrangement; whether that advantage is worth the adapter and troubleshooting work depends on the printer’s layout.
#1 Best Overall
- 8-Port CAN Hub with a Spare Port for a Nearby Device
- Follows Linear CAN Bus Topology, Increasing Reliability
- ToqueCAN Compatible
What you need before installing CAN
- A CAN-capable toolboard: confirm that its MCU has a CAN transceiver. The MCU family alone does not establish that a particular board has the required hardware.
- A host connection: use a USB-to-CAN adapter, or a supported MCU configured as a USB-to-CAN bridge. Klipper recommends verifying that an adapter’s firmware can be updated and notes Candlelight-compatible options.
- Compatible firmware and matching settings: flash the board with CAN firmware and make sure the host and toolboard CAN settings agree.
- Correct wiring and termination: follow the board’s documentation for CANH, CANL, power and ground, and provide exactly two 120-ohm terminators at the ends of the physical bus.
- A way to identify the node: Klipper’s
canbus_query.pyscript discovers an uninitialized node so its CAN UUID can be used in the printer configuration.
Install and configure the CAN connection
- Check the board and host hardware. Choose a CAN toolboard with a CAN transceiver, then select a USB-to-CAN adapter or a supported MCU for bridge mode.
- Build and flash CAN firmware. Configure the toolboard for CAN and keep its CAN settings consistent with the host. If using bridge mode, set the CAN frequency when building the bridge firmware.
- Configure Linux’s CAN interface. Klipper’s documented Linux example uses the
can0interface at 1,000,000 bits per second. In USB-to-CAN bridge mode, Linux CAN timing options are ignored because the frequency is selected at firmware build time. Klipper recommends 1,000,000 bits per second for bridge mode, where the bridge and CAN devices share bus bandwidth. - Wire the bus and fit the terminators. Follow the toolboard documentation for polarity and power connections. Put one 120-ohm terminator at each physical end of the bus, not at every node.
- Check termination with power removed. Measure between CANH and CANL. A correctly terminated bus should measure about 60 ohms, the parallel result of two 120-ohm resistors.
- Find the toolboard UUID. Run Klipper’s
canbus_query.pyto discover an uninitialized node, then add itscanbus_uuidtoprinter.cfgin the appropriate CAN MCU configuration. Follow the board’s setup instructions for the exact configuration syntax.
A USB-to-CAN bridge board is configured as a CAN connection, not as a USB serial device: it does not appear as a device under /dev/serial/by-id, and its printer configuration should not use a serial: entry.
Check these issues if the node is missing
- The Linux interface is down or unavailable: confirm that
can0is enabled and check whether the adapter or bridge is operating. In bridge mode, resetting the bridge MCU can disablecan0. - The toolboard does not appear in UUID discovery: verify that it is powered, flashed with CAN firmware, wired with CANH and CANL in the correct positions, and using settings consistent with the host.
- The bus has the wrong termination: with power removed, check resistance between CANH and CANL. About 60 ohms is the expected reading for two correctly placed 120-ohm terminators.
- A bridge seems absent from another adapter’s node list: the USB-to-CAN bridge itself is not seen as a separate bus node by other adapters. Distinguish the bridge’s host-interface role from the CAN nodes attached to it.
- The UUID is known but Klipper cannot connect: confirm that the UUID in
printer.cfgbelongs to the intended, initialized toolboard and recheck interface state, bitrate consistency and termination before investigating printer motion.
When CAN is worth the extra work
Choose CAN when a remote toolboard meaningfully simplifies a moving toolhead’s wiring, when you want to add multiple remote boards, or when a modular toolhead connection is valuable for your setup. Choose USB when a single remote MCU already meets your needs and minimizing configuration work matters more than reducing the toolhead’s signal-wire bundle.
Rank #2
- 6-Port CAN Hub for Toolchanger 3D Printers
- Follows Linear CAN Bus Topology, Increasing Reliability
- Designed for StealthChanger
- 6x 4-Pin Filament Sensor Connectors
- 6x Thermistor Connectors
Klipper’s CAN documentation recommends two 120-ohm resistors between CANH and CANL. An EBB36 or EBB42 CAN toolboard is one documented example of toolhead-side hardware; check the documentation for the specific board revision before wiring or configuring it.
Quick Recap
Rank #3
- 4x Stepstick Slots for TMC2209-based Stepsticks (Stepsticks Not Included)
- 4x Brushed DC Motor Drivers
- 4x ARGB LED Connectors
- 12x Endstop Connectors
- 1x 5V Fan Connector (No Speed Control)
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