CAN-Bus only Setup

repman

I want to build-up an extruder test stand. So I only have a CAN-Toolboard which is connected to my RaspberryPi via CAN-Bus. I attached a CAN-Hat to the RPi. This bus setup works so far. I see the toolhead on the CAN-Bus, kommunication works.

Now I want to control the toolhead with Repetier-Server (heat-up, temp-control, fans, extruder, etc.). How can I achieve that?
I do not have a printer controller board attached, so I need something like a virtual printer (with or without X-Y-Z-steppers).
How is the connection method to Repetier-Server?

I setup a klipper instance with the can-Bus enabled:

[canbus]
interface: can0
[include SHT36V3.cfg]

and:

[mcu SHT36V3]
## CAN ID
# canbus_uuid=b1234fa7dabc, Application: CanBoot
canbus_uuid: b1234fa7dabc

Under printer settings>connection nothing is accepted but "Serial Connection".
What do I have to choose?

Repetier

In Repetier Server you always set the serial connection to the virtual serial connection klipper it self creates. When you install Klipper using our interface, the path is normally set by default. Something like
/var/lib/klipper/sockets/<slugName>

Normal klipper install would use /tmp/printer I think, but there are some issues nowadays with /tmp and special permissions.

repman

OK, but that is not the problem. As I do not have a printerboard I made the settings as you suggested. I setup a serial connection to a socket /var/lib/klipper/sockets/Test.api.
In klipper I made a dummy configuration (A "minimal printer")

# This is the default configuration for the printer: Test
# This option is needed if you want to use the recover feature so that Repetier-Server can manually set the z position in Klipper
[force_move]
enable_force_move: true
[mcu]
serial: /var/lib/klipper/sockets/Test.api
[printer]
kinematics: none
max_velocity: 1
max_accel: 1

This is a empty printer. But RS is not able to communicate with it. In console there is written over and over again:
Recv:20:53:45.849: // Printer is not ready
Recv:20:53:45.849: // The klippy host software is attempting to connect. Please
Recv:20:53:45.849: // retry in a few moments.
Recv:20:53:45.849: !! Printer is not ready

Here is /tmp/klippy_Test.log:

Restarting printer
Start printer at Tue May  5 21:27:54 2026 (1778009274.9 6438.7)
===== Config file =====
[force_move]
enable_force_move = true

[mcu]
serial = /var/lib/klipper/sockets/Test.api

[printer]
kinematics = none
max_velocity = 1
max_accel = 1
=======================
mcu 'mcu': Starting serial connect
mcu 'mcu': Unable to open serial port: [Errno 6] could not open port /var/lib/klipper/sockets/Test.api: [Errno 6] No such device or address: '/var/lib/klipper/sockets/Test.api'
webhooks client 4129576592: New connection
webhooks client 4129576592: Client info {'name': 'Repetier-Server Pro 1.4.18'}
mcu 'mcu': Unable to open serial port: [Errno 6] could not open port /var/lib/klipper/sockets/Test.api: [Errno 6] No such device or address: '/var/lib/klipper/sockets/Test.api'
mcu 'mcu': Unable to open serial port: [Errno 6] could not open port /var/lib/klipper/sockets/Test.api: [Errno 6] No such device or address: '/var/lib/klipper/sockets/Test.api'

repman

The question is: How can I communicate with the Raspberry Pi - Part of klipper without the firmware on a printerboard?
As I said before: I just want to send commands to an adapted CAN-Toolboard which has an extra MCU on board (RPi2040 in my case)?

repman

Found it out myself:
You need at least one entry [mcu] in printer.cfg. So [mcu my_mcu] does not work if you dont have a master [mcu] entry.
If you have no printer and only a CANbus Toolhead, you must provide a CAN-UUID in the master [mcu]. Then it works:

[force_move]
enable_force_move: true

[mcu]
# serial: /var/lib/klipper/sockets/Test.api
canbus_uuid: <CANBus UUID> 

[printer]
kinematics: none
max_velocity: 1
max_accel: 1

Anyway: Excuse my lack of knowledge

BTW: There is a lot of SPAM in this forum, right?

Repetier

Yes, there is a constant flood of spam, and I'm always trying to catch them as soon as I see them.