Midi SysEx Messages



am I correct in assuming that currently it is not possible to send SysEx messages with Sonic Pi?


You can send raw midi so probably can that way though I’ve not investigated it.


Yes, I have seen that. The thing is that I need to send something like:

F0 00 20 6B 7F 42 02 00 **01 70 09** F7 (source)

and up to now I have not spotted how to translate this to something like

midi_raw 0xb0, 0x79, 0x0  # example from Sonic Pi doc

accepting only 3 bytes. As far as I understood sysex commands contain more than 3 bytes (as in the example above, where the mere midi control data bytes are #9 to #11).


Great question. It should work, but I have to confess to not having tried it myself, so it’s possible there’s a bug somewhere.

I’m currently on the road, so it’s a bit hard for me to try something out right now, but please pester me if I don’t get back to you on this.


First time I tried, it did not work. But I’ll give some more effort tomorrow. Maybe I did someting wrong.

If I understand correctly I will just have to spit up the command in 3 groups, right?

Thanks for the input, @samaaron !


Hi Sam,

if you have the time I’d like some help about this issue. I have confirmed that I can trigger the controller by using amidi. F. e. I can send the following message to trigger a pad’s LED to on:

 amidi -p hw:2 -S 'F0 00 20 6B 7F 42 02 00 10 77 01 F7'

I tried different versions but I do not manage to send the same command using Sonic Pi’s midi_raw.

Some obvious questions:

  • How do I divide the command (if at all); midi_raw expects 3 bytes (or at least parts) if I interpret the documentation correctly: “midi_raw a (byte), b (byte), c (byte)”
  • Do I need the sysex delimiters F0 ... F7?
  • Do I need the hex prefixes 0x; if yes: for all bytes?
  • Finally - and an answer to the questions before: Could you give an example using the above mentioned sysex command I sent with amidi that I could try?

I’d be very grateful for some help on this issue.



I’m in Australia for a couple more weeks. Hopefully I’ll an opportunity to look into this before Christmas.


Yes, I know. Have a nice stay. No hurry with that.


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