Roland S-330 Owner's Manual page 152

Roland
Exclusive
Messages
Bil
Data
Format
for
Exclusive
Messages
Roland's MIDI implementation uses the
following data
format
for all
exclusive
messages
(type IV)
:
#
One- way
transfer
procedure
(See
Section3
for
details.)
This procedure
is
suited
for
the transfer of a small
amount
of
data.
It
sends
out
an
exclusive
message completely independent
of a receiving device
status.
Byte Description
FOH
Exclusive status
41H Manufacturer
ID
(Roland)
DEV
Device ID
MDL
Model
ID
CMD
Command
ID
[BODY] Main data
F7H End
of exclusive
Connection Diagram
Device (A)
Connectionat point2
is
essential for
"Request data"
(See Section3.)
Device (B)
MIC4
IN
a
MIDI
OUT
procedures.
# MIDI status
#
Model-
ID
FOH,
F7H
An
exclusive
message must
be flanked by a
pair
of
status
codes, starting with a
Manufacturer-
ID immediately after
FOH
(MIDI vcrsionl.O).
# Manufacturer-
ID
:
41
The Manufacturer-ID
identifies the
manufacturer
of
a MIDI
instrument
that
triggeres an exclusive message. Value
41H
represents Roland's Manufacturer -ID.
# Device-
ID
;
DEV
The Device
-ID
contains a unique value
that identifies
the
individual device
in
the multiple implementation of MIDI
instruments.
It is
usually set to
00H -
OFH,
a value smaller
by
one
than that of a basic channel, but value
00H
—
1FH
may
be used
for
a device with multiple
basic
channels.
MDL
The Model-
ID contains a value thai uniquely
identifies
one
model from
another. Different models, however,
may
share
an
identical
Model
-ID
if
they
handle
similar data.
The Model -ID
format
may
contain
00H
in
one
or
more
places
to
provide an extended
data
field.
The
following are
examples
of valid
Model -IDs, each representing
a
unique model:
01H
02H
03H
00H.
OIH
00H, 021
00H, 00H,
01H
#
Command-
ID
:
CMD
The
Command -ID
indicates the function of
an
exclusive
message.
The Command -ID
format
may
contain
00H
in
one
or
more
places to
provide an extended
data field.
The
following
are examples
of valid
Command
-IDs
,
each
representing a unique function
:
OKI
02H
0311
0011,
til
00H,
02H
OOH,
0011.
01H
#
Main
data
.-
BODY
This
field
contains
a
message
to be
exchanged
across
an
interface.
The
exact data
size
and
contents
will
vary with the
Model
-ID
and
Command
-ID.
#
Handshake-
transfer procedure (See Section4 for
details.)
This procedure
initiates a
predetermined
transfer sequence
(handshaking)
across the interface before data transfer
takes
place.
Handshaking ensures
that reliability
and
transfer speed
are high
enough
to
handle a large
amount
of data.
Connection Diagram
Device (A) Device (B)
MIDI OUT
MIDI IN
*
MIDI
IN
MIDI
OUT
*
7
Connectionat points!
and
2
is
essential.
Notes on the above two
procedures
There
are separate
Command -
IDs
for
different
transfer
procedures.
*DevicesA and B cannot exchange
data unless they use
the
same
transfer procedure, share
identical
Device-ID and
Model
ID,
and
are ready for
communication.
One-way
Transfer Procedure
This procedure sends out
data
all
the
way
until
it
stops when
the messages are so
short that
answerbacks need
not be
checked.
For long messages, however,
the receiving device must
acquire
each message
in
time with the
transfer sequence, which
inserts
intervals of
at least
20milliscconds
in
between.
Message Command
ID
Request data
1
Data
set
1
RQ1 (11H)
DTI (12H)
^[
|
Address-
mapped
Data Transfer]
Types of Messages
#
Request
data
#1
:
RQ1 (11H)
This message
is
sent out
when
there
is
a
need
to acquire
data
from a device
at the
other end of the
interface.
It
contains
data
for
the address and
si2e that specify designation and
length,
respectively, of data required.
On
receiving
an
RQ1
message,
the remote device checks
its
memory
for the data address
and
size
that satisfy
the
request.
If it
finds
them and
is
ready for communication, the device
will
transmit a "Data
set
1
(DTI)" message, which
contains
the
requested
data. Otherwise, the device
will
send out
nothing.
Address mapping
is
a technique for transferring
messages
conforming
to the data format given
in
Section
1.
It
assigns
a series of
memory
-resident records
—
waveform and
tone
data, switch status,
and
parameters, for
example
—
to
specific
locations in a
machine-dependent address
space, thereby
allowing access to data residing
at
the address a message
specifies.
Address
-mapped
data
transfer
is
therefore independent of
models
and
data categories. This technique allows use
of
two
different transfer
procedures
:
one-way
transfer
and
handshake
transfer.
Byte Description
FOH
Exclusive status
41H
Manufacturer
ID
(Roland)
DEV
Device
ID
MDL
Model
ID
11H
Command
ID
aaH Address
MSB
LSB
ss.H
Size
MSB
LSB
sum Check sum
F7H End
of exclusive