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serialosc runs in the background and converts serial communication (over USB) into OSC. Applications can query serialosc to connect to the grid and arc.

How it works


Usually, you will not interface with serialosc directly – instead, you’ll likely use a library as an intermediary, like the [serialosc] object in Max or the monomeSC library for SuperCollider. Over the years, libraries have been spun up for a lot of environments and languages – see our grid studies for more about these.

The rest of this document details what these pre-made libraries abstract, for those curious about the underlying mechanics or who wish to build their own.


serialoscd keeps watch for connection and disconnection of devices. When connected, a new process is launched ‘serialosc-device’ which communicates on its own port.

We will assume a theoretical application on port 6666 on localhost is trying to connect to serialosc. We’ll also assume you have liblo installed, which includes oscsend and oscdump.

First, connect your grid to your computer. Then, open a terminal window and set up an OSC monitor:

  • oscdump 6666

Open another terminal window. To list the available devices, we’ll query serialoscd which listens on port 12002, and we’ll route the response to our monitor:

  • oscsend localhost 12002 /serialosc/list si localhost 6666

Say we have an 8x16 grid attached, results might look like this:

  • e83daeee.d2ea63b5 /serialosc/device ssi "m46674021" "monome 128" 17675

Here, port 17675 is where the device is listening. To have this grid send to our application:

  • oscsend localhost 17675 /sys/port i 6666

Now when keys on the grid are pressed we should see something like:

<timestamp> /monome/grid/key iii 9 3 1
<timestamp> /monome/grid/key iii 9 3 0

…which follow the form /prefix/grid/key x y z. Note, that while the “prefix” defaults to /monome, it’s changeable with any string. For example, to change our prefix to /blinky:

  • oscsend localhost 17675 /sys/prefix s "/blinky"

Note that this prefix is saved in your computer’s serialosc preferences so that when this grid is disconnected + reconnected, its prefix will remain the defined value. To your grid’s prefix change back to default:

  • oscsend localhost 17675 /sys/prefix s "/monome"

To send LED data:

  • oscsend localhost 17675 /monome/grid/led/level/set iii 2 2 8 (set LED 2,2 to brightness 8)
  • oscsend localhost 17675 /monome/grid/led/all i 0 (clear the grid)

See OSC for the complete list of messages.

All ports are also discoverable via zeroconf as _monome-osc._udp.


serialoscd will save a preference file for each monome device connected to your computer, where prefixes and other information about your device are stored long-term.

The filepath to this folder varies depending on your operating system:

  • Linux: $XDG_CONFIG_HOME/serialosc or $HOME/.config/serialosc
  • macOS: ~/Library/Preferences/org.monome.serialosc
  • Windows: $APPDATA\\Monome\\serialosc

Inside this folder, you see .conf files with each device’s serial number (eg. m93274581.conf), wherein you’ll find the device’s persistent settings:

server {
  port = 17218
application {
  osc_prefix = "/monome"
  host = ""
  port = 7778
device {
  rotation = 0

If you ever need to start fresh, you can simply delete the corresponding .conf file and serialoscd will generate a new profile using the default settings.