Octoprint Connection Guide

Octoprint is a popular web interface for 3D printers that provides remote control and monitoring capabilities.

There are 3 different ways to connect Octoprint to Smoothie:

Ethernet - Network connection via socat
USB - Direct USB serial connection
UART pins - Serial connection via UART pins

Connecting via Ethernet

Octoprint can’t connect via network natively, so we’ll use socat (a fork of famous netcat) to create a local pipe to route traffic to Smoothie.

Step 1: Install socat

First install it (all the following examples are for OctoPi):

sudo apt-get install socat

Step 2: Test the socat connection

Now try this command (replace SMOOTHIE_IP with your Smoothieboard address, like 192.168.0.10):

sudo socat pty,wait-slave,link=/dev/ttySmoothie,perm=0660,group=tty tcp:SMOOTHIE_IP:23

You’ll see no output (that’s ok). Leave the command running. We’ll finalize that later.

Step 3: Configure Octoprint

Proceed to Octoprint Web UI.

Go to OctoPrint Settings → Serial Connection:

Set Additional serial ports to /dev/ttySmoothie
Save, then reopen the same settings page
Set Serial Port to /dev/ttySmoothie
Set Baudrate to maximum: 250000
Save and close

Step 4: Test the connection

Now try to connect to the printer. If it connects, we should finalize the configuration and add socat to system startup.

Step 5: Make socat persistent

Open /etc/rc.local:

sudo nano /etc/rc.local

Go down with the ↓ key until you reach the end of the file. The last line is usually exit 0.

Before this line add the following (replace SMOOTHIE_IP with Smoothie IP address):

socat pty,wait-slave,link=/dev/ttySmoothie,perm=0660,group=tty tcp:SMOOTHIE_IP:23 &

Save & exit: Ctrl+O, Enter, Ctrl+X.

Reboot and check if it works.

Performance Note: Ethernet Can Be Slow

Performance Warning: Try to print (stream) some file from Octoprint (not from Smoothie's SD card). You may notice that it streams gcode awkwardly slow even on a fast network connection. This is a known issue for some users, which means you should prefer USB to Ethernet connection for best performance.

It might be working for you. Please leave a note somewhere if the speed is fine via socat.

Still, you can upload to SD (slow too: 1 MB/min for some users) and use Octoprint to start/stop jobs and control printer status.

Connecting via USB / UART

Recommended Method: USB connection is generally faster and more reliable than Ethernet for Octoprint.

Detailed instructions are described on Octoprint wiki at Setup OctoPrint with Smoothie.

Important Setting

Set the “Ignore any unhandled errors from the firmware” setting in Octoprint to ensure smooth operation with Smoothie.