Roland U-20 Owner's Manual page 180

Roland Exclusive
Messages
Data Format for Exclusive
Messages
Roland's
MIDI impiementatian uses
the
followinE data
format
for
all
exdusive messages
(type IV)
Byte DescriDtlon
FOH
Exclusive
status
41
Manufacturer
!D CFlaland}
DEV
Device ID
MDL
Model ID
CMD
Command
ID
[BODY]
-
Main data
F7H
End
of exclusive
#
Model
-
ID
:
#
MIDI
status
:
FOH,
F7H
An
exclusive
message must be flanked
by
a pair of status
codes, starting
with a
Manufacturer- ID immediately
after
FOH
(MBDI
versionl.0).
#
Manufacturer
-
ID
:
41
The
Manufacturer
-
ID identifies
the manufacturer of
a MIDI
instrument that triggers
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
uaially 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.
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
02H
03H
OOH,
OIH
OOH.
02H
OOH, OOH,
OIH
# Command
-
ID
:
CMD
The
Ckimmand -
ID Indicates the function
of an exclusive
message.
The
Command
-
ID 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
OIH
02H
03H
OOH.
OIH
OOH,
02H
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.
Address
-
mapped
Data Transfer
Address mapping
is
a technique
for
transferring
messages
conforming
to
the data
format given
In Section
1. It
as^gns
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.
Thb
technique allows use of
two
different transfer
procedures
:
one -
way
transfer
and
handshake
transfer.
# 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.
Comiaation Diagram
De^^ce (A) Device (B)
mx
OUT
'
»
MttX IN
MO
OUT
2
Connection at point 2
is
essential
for
procedures. (See Section
3.)
'
Request data
"
#
Handshake
transfer
procedure (See Section
4
for
details.)
This procedure
initiates
a
predetermined
transfer
sequence
(handshaking) across the interface
before data transfer takes
placa Handshaking ensures
that reliability
and
transfer
speed
are high
enough
to
handle a large
amount
of data.
Conrwctim Diagram
Device (A)
Device (B)
Mm
IN
Mn>
CHTT
__L^
MO
IN
MO
OUT
*
2
Connection at points
1
and 2
is
essential.
Notes on
the above two procedures
There
are separate
Command
-
IDs for 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
answcrbacks need
not be checked.
For long messages,
however, the receiving device
must
acquire
each message
in
time with Uie transfer sequence,
which
inserts
intervals
of
at least
20 milliseconds
in
between.
Msssage
Command
ID
Request
data
1
Data set
1
RQ1 (11H)
DTI (12H)
Types
of
Messages
#
Request data
#1
:
RQ1
C11H)
This message
is
sent out
when
there
is
a need
to
acquire data
from a devica
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
reguesL
If it
finds
them and
is
ready for
communication, the device
will
transmit a "Data set
1
(DTD"
message,
which contains the
requested data.
Otherwise, the device will
send out nothing.
Byte Description
FOH
Exciuslve status
41
Manufacturer
ID
(Roland)
DEV
Device ID
MDL
Model
ID
UH
Command
ID
bbH Address
MSB
1
LSB
ssK
Size
MSB
LSB
sum Check sum
F7H
End
of exclusive
178