Roland Exclusive Messages
Data Format for Exclusive Messages
Kolanil's MIDI imiilcmGntation usos the following data format for all
exclusive messages (type IV) :
# One-way transfer procedure (See Section
3 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.
8yte
Description
FOH Exclusive
status
41H Manufacturer ID (Roland)
DEV Device ID
MDL Model
ID
CMO Commancf
iO
[BODY] Main
data
F7H
End of exclusive
Conn«ction
Diasram
Device (A) Device
<6)
Mia
OUT ma IN
MIDI OUT
Connection at point 2 is essential for
Section
-3.)
"Request data" procedures.
(See
#
MIDI status :
FOH. F7H
An
exclusive
message
must be flanked by a pair of status codes, starling
with
a Manufaciurcrll) immediately
after FOH (MIDI versionl.O).
# Manufacturer-ID :
41
H
The Manufaciurcrll) ideniifies
the manufacturer of a MIDI instrument
ihai
uiKMcrs an exclusive message. Value
4IH represents Roland's
Manufacturer
!D.
# Device-ID : DEV
The Device 11)
contains a unique value that identifies
the
individual device
in the multiple implementaiion
of MIDI instruments.
It is usually set to
0011 oi'II. a value
smaller by one than that
of a
basic channel,
but
value 0011
li'H may be used for a device with
multiple basic channels.
# Model-ID
:
MDL
The
M<xIcllD
contains a value
that uniquely identifies one model from
anoihcr.
Different models, however,
may share an identical Model-ID if
they handle simitar
data.
The ModeilD formal
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
:
Olil
0211
o:m
OOli. OIH
00 i I. 0211
0011. OOH. 0111
# Command-ID :
CMD
The Command
ID
indicates
the function of
an
exclusive
message. The
CummandlD formal
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:
ONI
02il
0311
OOH. OIH
OOH. 0211
OOH. OOH. OIH
# Main data : BODY
This field contains
a message to
be exchanged across an interface.
The exact
daia sixe and contents will vary with
the Model-ID and
Command II).
# Handshake-transfer procedure
(This device
does not cover this procedure)
This procedure
initiates a predetermined transfer sequence (handshaking)
acnass the interface before data transfer takes
place. Handshaking ensures
that reliability and transfer speed are high enough to handle a large
amount of data.
Connaotion Diagram
Device (A) Device
(B)
MO OUT
MIDI m
MIDI IN
MIDI OUT
*
2
Connection at points 1 and 2 is essential.
Notes on the above tv\fo procedures
* There are separate Command-IDs
(or different transfer procedures.
* Devices
A 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
and is used
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 20 milliseconds in between.
Tvp«*
of Motaaga*
Message Command ID
Request
data
1
Data set 1
RQl (IIH)
DTI (12H)
# Request data #1 : RQl (IIH)
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 RQl 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 wilt
send out nothing.
Address-mapped
Data Transfer
Address mapping
is a technique
for transferring messages conforming
1(1 the data format given
in
Section I. It assigns a series of memory-
resident rcc<irds waveform
and tone
data,
switch
status, and parameters,
(or example
to specific locations
in a machine dependent
address space,
thereby allowing
access lo data
residing at the address a message
siwcifies.
A<ldress
mapix;d
data transfer is therefore
independent of models and
daia caiexorics.
This technique allows
use of two different
transfer
procedures
: oneway
transfer and
handshake transfer.
Byte
Description
FOH Exclusive
status
IIH
Manufacturer ID (Roland)
DEV
Device ID
MDL
Model ID
IIH Command ID
aaH
Address MSB
LSB
ssH Size
MSB
LSB
sum
Check sum
F7H End of exclusive
197
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