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Query Devices

Mainsail can list connected CAN, Serial, USB, and Video devices to help you find the correct hardware paths for your configuration. This is useful when setting up your printer or webcam.

To access the device list, open any config file in the editor and click the Devices button in the toolbar.

CAN Devices

This tab displays unassigned CAN nodes on your network. Each entry shows the application type (Klipper or Katapult) and the UUID.

CAN Devices
Find devices dialog with CAN devices

Unassigned Nodes

An "unassigned" node is a CAN device that has not been activated by Katapult or Klipper. Once Klipper or Katapult connects to a node, it receives a Node ID and will no longer respond to queries. A device reset is required to make it queryable again.

Multiple Unassigned Nodes

When multiple unassigned nodes are on the network, queries can cause arbitration errors. It is recommended to only query when a single unassigned node is on the network. If you need to query multiple nodes, reset all nodes before running Klipper.

For more details, see the Moonraker CAN documentation.

Serial Devices

This tab shows serial connections to your printer mainboard. Use these paths in your printer.cfg for the [mcu] section:

Serial Devices
Find devices dialog with Serial devices
[mcu]
serial: /dev/serial/by-id/usb-Klipper_...

USB Devices

This tab is intended for debugging. It shows whether the system recognizes connected USB devices, which can help troubleshoot connection issues.

USB Devices
Find devices dialog with USB devices

Video Devices

This tab lists all libcamera and V4L2 webcams connected to your system. It also displays available resolutions and video formats for each device, which is useful when configuring webcams in Crowsnest or Mainsail.

Video Devices
Find devices dialog with Video devices