Main Types Of Midi Data Used By The Spd-20X - Roland Octapad SPD-20X Owner's Manual

MIDI connectors
MIDI allows you to independently control two or more devices over a single MIDI cable. This is possible
because MIDI provides for multiple channels of control. You can think of MIDI channels as being similar
to television channels. Although many broadcast channels are in the air at any one time (many channels
of MIDI data are moving through a single cable), a television set receives only the channel to which it is
set (the MIDI device receives only the channel to which it is set).
TV Station A
TV Station B
TV Station C
TV messages from various TV Stations are sent through the antenna's cable.
MIDI provides sixteen channels, 1–16, and the receiving device will only receive data when its receive
channel matches the Transmit Channel. In the following diagram, playing the keyboard will cause only
sound module B to play.
MIDI OUT
Transmit channel: 1
With the SPD-20X, you can set the MIDI Channel (MIDI CH).
MEMO

Main Types of MIDI Data Used by the SPD-20X

A wide variety of musical data can be transmitted by MIDI, with a different type of MIDI message
provided for each type of data. MIDI messages can be broadly categorized into two groups: information
that is differentiated by channel (Channel messages) and information that is not differentiated by
channel (System messages).
Data differentiated by channel (Channel messages)
These messages carry musical performance data. Normally, these messages do most of the work. The
result that each type of message produces will depend on the settings of the sound module.
• Note messages
These messages notify the sound generator that a pad has been struck. (A keyboard would transmit
these messages when keys are played.) Note messages convey the following information.
Note Number: Each note message (Note On or Note Off ) carries the Note Number which was assigned
to that pad (a number indicating the note position on a keyboard).
Note On: This message is transmitted when a pad is struck (when a key is played).
Note Off: This message is transmitted when the specified Gate Time has elapsed after the Note On
message (when a key is released).
Velocity: Each note message contains data indicating how strongly the pad was struck (how strongly
the key was played).
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Select the channel of the TV Station
you wish to watch.
Sound Module A MIDI IN
Receive channel: 2
Sound Module B
Receive channel: 1
MIDI THRU
MIDI IN