Sysex, or system exclusive data is a MIDI message specific to one device. This information may be a patch change or all of the data needed to define a bank of sounds in a synth. Sysex data is sent to a particular instrument by the first part of the MIDI message’s header. The header includes the manufacturers ID and the devices ID. If there is two or more of the same device they will both respond to the messages; to prevent this form happening change one unit’s device ID. Sysex data is usually very dense compared with normal midi commands and therefore can cause noise or delays in midi communication if it is sent while a sequence is playing back.
As an example, Unisyn can use Sysex to edit and manage the patches of a Roland JV 1080. It sends a bank request message, and then stores the JV 1080′s information on the computer’s hard drive. You can then edit and categorize the sounds and send them back to the JV 1080 via Sysex.