Logic Pro 9 User Manual - Help Library - Apple

Although you can have any number of messages (of any kind) in the SysEx fader’s Event
List, there is only one fader value, and all selected messages adopt this value.
You can use a similar method to create any kind of MIDI or meta event in the SysEx fader
window. Command-clicking any of the eight event type buttons (Note, Program Number,
Pitch Bend, Controller, Channel Pressure, Poly Pressure, SysEx, and Meta Event) creates a
new event of that type. Meta events can be created by using the expanded view button,
featuring the 0’s and 1’s on its face.
The terms SUM (for the checksum) and VAL (for the fader value) being sent are displayed
within the SysEx string.
To set the checksum and value of a SysEx event
1 Select the events you want to alter.
2 Choose options from the Checksum and Value menus (found in the lower-right corner
of the window) to set the format of these bytes.
Checksum Format
A checksum can be created in any of the following formats:
• Roland
• Yamaha
• Regular Checksum
• 2’s complement
• 1’s complement
If you don’t know which one works with your MIDI device, try “off” (= no checksum) first
or “2’s complement.”
Value Byte Position
Position allows you to determine the position of the value byte. This position is specified
in bytes, counted from the end of the message: “last” refers to the position directly before
the EOX byte, “Last-1” indicates the byte before that, and so on.
Auto ensures that the value byte is inserted at the last position in the SysEx string if no
checksum was selected, or—if a checksum value was entered—that the value is inserted
as the second-to-last byte.
Value Byte Format
The following table outlines the resulting data format of the value option you send:
Value option
Auto
Result
1114 Chapter 37 Environment Objects Reference
The value is sent as one byte if the value range maximum is 127 or
less. If the maximum is higher than 127, the value is sent as two
bytes, the MSB (most significant byte) first.