Hi, I made 2 simple classes that allow to send/receive SysEx messages on ChucK: https://bitbucket.org/mariobuoninfante/sysex/src/master/ All they do it's basically sending/receiving messages via OSC to/from Pure Data that deals with actual SysEx messages. It seems to work fine, but I didn't do any 'stress test'. Of course having to convert from/to OSC is a kind of a bottleneck, so I'd expect some 'performance issues' when dealing with big SysEx messages (ie firmware updates) , but I think it's fine for general purpose SysEx transmissions. I'd like to see, one day, these 2 classes (SysExIn and SysExOut) being part of the ChucK source code as members of the MIDI classes family. Let me know if you have any question. Cheers, Mario