Alesis DM5Pro Kit Specifications download pdf (Page 159)

MIDI Supplement

DM PRO REFERENCE MANUAL 1 5 9

SYSTEM COMMON MESSAGES

Intended for all units in a system, some of these MIDI messages are:

Song Position Pointer. This indicates how many “MIDI beats” (normally a

16th note) have elapsed since a piece started (up to 16,384 total beats). It is primarily

used to allow different sequencers and drum machines to auto-locate to each other so

that if you start one sequencer, the other device will automatically jump to the same

place in the song, whereupon both continue on together.

System Exclusive. This message (called SysEx for short) is considered

“exclusive” because different manufacturers send and receive data over MIDI which

is intended only for that manufacturer’s equipment.

Example: Sending a QS6.1

message to an Alesis DM Pro Drum Module won’t do anything, but the message will

be understood by another QS6.1. This data often contains information about

individual instrument programs.

Timing Clock. A master tempo source (such as a sequencer) emits 24 timing

messages (clocks) per quarter note. Each device synchronized to the sequencer

advances by 1/24th of a quarter note when it receives the clock message, thus

keeping units in sync after they’ve both started at the same time. Many devices

subdivide this clock signal internally for higher resolution (e.g., 96 pulses per quarter

note).

Start. Signals all rhythmically-based units when to start playing.

Stop. Signals all rhythmically-based units when to stop playing.

Continue. Unlike a Start command, which re-starts a sequencer or drum machine

from the beginning of a song each time it occurs, sending a Continue message after a

Stop command will re-start units from where they were when they stopped.

(Portions of this appendix are abridged versions of material from Power

Sequencing with Master Tracks Pro/Pro 4

and The Complete Guide t o

the Alesis HR-16 and MMT-8

Publications, and are adapted with permission.)

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Alesis DM5Pro Kit Specifications Page 159