Yamaha PortaSound PSS-51 Owner's Manual page 44

Ө Types of MIDI Messages
MIDI devices communicate channel messages and system
messages. Channel messages carry performance informa-
tion such as a channel number and specific data to
control or produce sound. Channel messages include
NOTE OFF, NOTE ON, PITCH BEND CHANGE,
CONTROL CHANGE, and PROGRAM CHANGE.
System messages apply to the entire MIDI system rather
than a particular channel. System messages are typically
used for synchronization purposes, controlling
sequencers, resetting MIDI devices, and obtaining overall
information. These messages include CLOCK, START,
STOP, and ACTIVE SENSE. The sections below provide
simple descriptions of these data as implemented in the
PSS-51.
* NOTE ON/NOTE OFF
These messages are transmitted whenever a note is
pressed or released. The data also includes the note and
velocity for each channel.
* PITCH BEND CHANGE
This message indicates a change of pitch generated from
the WHEEL function.
* CONTROL CHANGE
These are messages that contain information about MODU-
LATION (VIBRATO), VOLUME, SUSTAIN, and REVERB
characteristics.
* PROGRAM CHANGE
These messages concern VOICE changes. For the PSS-51,
the VOICE number and the MIDI program number are the
same. These numbers are not always the same for other
instruments, however. When changing VOICE numbers, be
sure to match the MIDI program number with the PSS-51
VOICE number. (Refer to the owner's manual of the
connected MIDI devices for detailed program information.)
* CLOCK
CLOCK messages include data that can be used to synchro-
nize the timing and tempo of MIDI instruments.
* START/STOP
These messages can be used to control the START/STOP
of MIDI instruments. For the PSS-51, these messages apply
to the SONG MEMORY function.
* ACTIVE SENSE
This message indicates that the MIDI device is no longer
connected to the system. For example, if a cable is un-
plugged during a MIDI performance, the lack of a MIDI
Signal is detected and sound generation is stopped auto-
matically. :
40
Ш MIDI CONNECTION
€ MIDI Connectors
There are three MIDI connectors: MIDI IN, MIDI OUT,
and MIDI THRU.
* MIDI IN
Receives data from another MIDI device.
* MIDI OUT
Sends MIDI data from the PSS-51 to another MIDI device. ~
* MIDI THRU
Sends out data received at the MIDI IN connector to
another MIDI device.
@ MIDI Cables
Use specialized MIDI cables to connect MIDI devices.
To prevent data transmission errors, do not use cables
that are more than 15 meters in length.