Roland Exclusive Messages
Ill
Data Format
for
Exclusive Messages I
Roland's
MIDI
implementation uses the following
data
format
for all exclusive messages
(type
IV)
:
Byte Description
F0H Exclusive
status
41H
Manufactures
ID
(Roland)
DEV
Device
ID
MDL
Model
ID
CMD
Command
ID
[BODY)
Maindata
F7H
End
of exclusive
# MIDI status : F0H,
F7H
An exclusive message must be flanked by a
pair
of
status
codes, starting with a
Manufactures-ID
immediately
after
FOH
(MIDI
versionl.O).
#
Manufactures-
ID
: 41 H
The
Manufactures-
ID
identifies the manufacturer of a
MIDI
instrument that triggeres
an
exclusive message. Value 41H
represents Roland's Manufactures-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
OOH
-
OFH,
a value smaller
by one than that of a basic channel, but value
OOH
-
IFH
may be used for a device with multiple basic channels.
#
Model-
ID :
MDL
The Model -
ID
contains a value
that
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
OOH
in one or more places
to provide
an
extended data field.
The
following
are
examples
of valid Model -
IDs,
each representing a unique model :
OIH
OZH
03H
OOH,
OIH
OOH,
OZH
OOH, OOH,
OIH
#
Command-
ID :
CMD
The
Command-ID
indicates the function of
an
exclusive
message.
The
Command -
ID
format may contain
OOH
in
one
or more places
to
provide
an
extended data field.
The
following
are
examples of valid
Command-
IDs , each
representing a unique function :
OIH
OZH
03H
OOH,
OIH
OOH,
OZH
OOH,
OOH,
OIH
# 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.
fllAddress-
mapped Data Transfer!
108
Address mapping is a technique
for
transferring messages
conforming to
the
data format given
in
Section I. 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.
#
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.
Connection Diagram
Device (A) Device
(8)
MIDI OUT
MIDI lN
MIDI
IN
MIDI
OUT
Connectionat pointZ is essential for "Request data" procedures.
(See
Section3.)
#
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
(8)
MID1
OUT
MIDI
IN
MIDI
IN
MIDI
OUT
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.
Ellone-
way
Transfer
Procedure I
Types
of
Messages
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 ZOmilliseconds
in
between.
Message
Command
ID
Request
data
1
RO1
(11H)
Data
set
1
DT1
(12H)
# Request
data
# 1 :
RQ1
(11 H)
· 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 size
that
specify designation
and
length,
respectively, of
data
required.
On receiving
an
RQI message, the remote device checks its
memory for the
data
address and size that satisfy the request.
If
it finds them arid is ready for communication, the device will
transmit a "Data set I (DTI
)"
message, which contains the
requested daia. Otherwise, the device
will
send out nothing.
Byte
Description
F0H
Exclusive
status
41H
Manufactures
ID
(Roland)
DEV
Device
ID
MDL
Model
ID
11H
Command
ID
aaH
Address
MSB
LSB
s~H
Size
MSB
LSB
sum
Check sum
F7H
End
of exclusive
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