There was a question on how to make a FX switcher with MidiBox:
I redirected the TS to this thread.
@RockRaver:
"... when you say I only need one DOUT, you're saying i'll only need 1/4th of the DOUTx4 unit, correct? That would make sense as each 74HC595 can control 8 relays, correct?"
Indeed when controlling 7 relays, you only need 1/4 of a DOUTx4 module.
Actually, the CORE could control the 7 relays directly from one of its output headers so DOUT is not needed then, but this is not directly supported by the MIOS software so I decided to use a DOUT.
See also:
http://www.ucapps.de/mbhp_dout.html
http://www.midibox.org/dokuwiki/flo#midibox