Hello, I would like to connect one of my PCs (OS linux) on a Marshall CODE 50 and take control via usb midi.

When I open /etc/dmmidi2 in read acces. Reading file char by char, I see information when I touch the buttons of the amp (PREFX, AMP, MOD, ...). I can find the information in CODE-Midi-Implementation-Chart-V2.1.pdf.

I usually get two or three bytes and cross it with the document.
But this frame is not in the form Start of Transmission> Header> Command> End of Transmission.

By against when I open /etc/dmmmidi2 in write access, I can not send any command.
After having turned on the amp, I sent the following sequence for RECALL PRESETS 05:
0xF0 0x00 0x21 0x15 0x7F 0x7F 0x7F 0x73 0x01 0x05 0xF7
or RECALL CURRENT SETTINGS:
0xF0 0x00 0x21 0x15 0x7F 0x7F 0x7F 0x72 0x01 0x00 0xF7
Start of Transmission> Header> Command> End of Transmission
This command does not seem to work. Is there an intermediary step?

Would it be possible to give me a typical sequence to the CODE or a document that will explain the procedure to operate (ON / OFF) one of the button (PREFX, AMP, MOD, ...) of the amp.
Thank you in advance.
Cordially.

yoann