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Using MIDI
MIDI channels
MIDI channels are easy to understand if we use the anal-
ogy of television
broadcasting.
Many television
pro-
grams are broadcast from many IV stations, and your TV
antenna receives all of them. By setting vour television to
the channel you want to watch, you can watch only the
desired program. The same idea applies to MIDI chan-
nels. The master device is somewhat like the broadcast
station, and the slave device is like a television receiver.
The MIDI messages carried by the MIDI cable are like
the programs that are transmitted from the broadcast
stations.
Station B
=
)
Station C. | emma
On a TV, the channel is selected which carries the program you want to watch.
If two or more
slave devices are connected,
set the MIDI
channel of each slave device to match the MIDI channel of
the master device.
MIDI
= y
d)
DI
IN
MI
J) THRU
Master
Slave
Slave
device
device
device
Omni
As we mentioned earlier, it is generally necessary for the channel
of the slave device to match the channel of the master device in
order for MIDI messages to be received. However, there is one
exception which you should know about; Omni on/off.
Omni on ..... MIDI messages of all channels will be received.
Omni off ..... only MIDI messages of the specified channel
will be received.
(Omni on)
MIDI messages
uf all channels
will be received
If you set the slave device to Omni on, it will receive MIDI
messages regardless of the MIDI channel on which the mas-
ter device transmits. However, when using a sequencer to
create a MIDI ensemble, you must turn Omni off if you want
cach part to be played independently. Since most MIDI in-
struments are able to make effective use of MIDI channel,
you will normally leave them set to Omni off.
Program change messages
Program Change messages are MIDI messages that select dif-
ferent sounds. Actually, these messages tell the receiving de-
vice to "switch to sound number so-and-so"; not to "switch
to a piano sound" (for example). The sounds of MIDI instru-
ments are numbered from 1 to 128 (these are referred to as
20
program numbers), and when a program change message is
received, the sound of the corresponding
program number
is selected. This means
that even for the same program
number,
different
instruments
will
produce
different
sounds. Make sure you know the correspondence between
the program numbers and the sounds of the slave device be-
fore you transmit program change messages to it.
Control change messages
These messages are used for greater musical expressiveness;
for example
by turning the chorus effect on/off or adjusting
the volume. Control change messages can be divided into
those that simply say "turn effect XYZ on/off", and those that
say "set effect XYZ to a setting of ABC".
MIDI messages used by the
HP-1700L/1700/900L/900
The HP-1700L/1700/900L/900 uses the following MIDI messages.
However, this will depend on how you set the "MIDI transmis-
sion/reception mode"
[P22 .
Note messages.....
are transmitted when you press a key; "play such a note at
such a volume until such a time".
Program Change messages.....
"switch to sound number **" is transmitted when you select
sounds.
Control Change messages.....
"activate the damper pedal effect" is transmilted when
you press the damper pedal.
"activate the soft pedal effect" is transmitted when you
press the soft pedal.
"activate the sostenuto pedal effect" is transmitted when
you press the Sostenuto pedal.
"Turn the chorus effect on/off" is transmitted when you
press [CHORUS]
on/off.
(P When the above MIDI messages are received, the HP-1700L/
'1700/900L/900 will take the appropriate action by playing a
note or controlling
an effect. However, the MIDI messages
actually used will depend on the "MIDI transmission/reception
mode" [P2 .
As a group, these messages are known as Channel messages,
and are handled independently for each MIDI channel. In ad-
dition to these, MIDI includes messages that are handled for
the entire system; system messages (for example, System Exc-
lusive messages).
System Exclusive messages
We mentioned earlier that MIDI is a world-wide standard,
but exclusive messages are an exception to this. Exclusive
messages are unique to each manulacturer. Unlike the
general-purpose messages we have been describing, these
messages are used to exchange information that is unique
to specific manufacturers or devices.
The HP-1700L/1700/900L/900 can use the following exclu-
sive message:
"Turn the reverb efíect on/off" is transmitted when
[REVERB] is turned on/off.
"Turn
the Multi
timbral
mode
on/off"
is transmitted
when holding (FUNCTION. and press (MULTI! .
These messages allow increased musical expressiveness,
but are not defined as one of the general-purpose con-
trollers. This is why Roland uses exclusive message to
cover this area. Of course, other types of instruments
will not be able to understand or transmit these particu-
lar messages.
t ——
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