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*
The
size
of
the
requested
dau
does
not
indicate the
number
of
bytes
that will
malce
up
a
DTI
message,
but represents the
address
fields
where
the
requested data
resides.
*
Some
models
are
subject
to
limitations
in
data
format used
for
a
single transaction.
Requested
data, for
example,
may
have
a
limit in
length
or
must
be divided
Into
predetermined
address
fields
before
it
is
exchanged
across
the
interface.
*
The
same number
of bytes
comprises
address
and
size data,
which,
however,
vary with
the
Model-ID.
*
The
error
checking process uses
a
checksum
that
provides
a
bit
pattern
where
the
least
significant
7
bits
are
zero
when
values
for
an
address,
size,
and
that
checksum
are
summed.
#Dataset1: DTI
(12H)
This
message
corresponds
to
the actual data transfer process.
Because
every
byte
in
the
data
is
assigned
a
unique
address,
a
DTI
message can convey
the
starting
address of
one
or
more
data as well as a
series
of
data formatted
in
an
address-
dependent
order.
41
Device
B
requesting data
from
Device
A
Device
B
sends an
RQl
message
to
Device A. Checking
the
message. Device
A
sends
a
DTI
message back
to
Device
B.
Device
(A)
Device
(B)
[Data
set
1]
-^
[Data
set
1]
^-
*
More
than
20m
sec time
internal.
[Data
set
1]
;
^-
[Data
set
1]
'
^-
-CRequest data]
The
MIDI
standards
inhibit
non-real time
messages from
interrupting
an
exclusive one.
This
fact
is
inconvenient
for
the
devices
that
support a "soft-through"
mechanism.
To
maintain
compatibility
with
such
devices,
Roland
has
limited the
DTI
to
256
bytes so
that
an
excessively long
message
is
sent out
in
separate
segments.
Byte
Description
FOH
Exclusive
41H
Manufacturer
ID
(Roland)
DEV
Device
ID
MDL
Model
ID
12H
Command
ID
aa
H
Address
MSB
LSB
SL
H
m
Da
Ch
ta
ack
sum
F7H
End
of
exclusive
*
A
DTI
message
is
capable of providing only
the valid
data
among
those specified
by
an
RQl
message.
*
Some
models
are subject to limitations
in
data
format used
for
a
single
u^nsaction.
Requested
data, for
example,
may
have
a
limit in
length or
must
be divided
into
predetermined
address
fields
before
it
is
exchanged
across
the
interface.
*
The number
of bytes
comprising
address data
varies
from one Model-ID
to
another.
*
The
error
checking process uses
a
checksum
that
provides
a
bit
pattern
where
the
least
significant
7
bits
are
zero
when
values
for
an
address,
size,
and
that
checksum
are
summed.
#Example
of
Message
Transactions
9
Device
A
sending data
to
Device
B
Transfer of a
DTI
message
is
ail
that
takes place.
Device
(A)
Device
(B)
[Data
set
1]
^-
*
More
than
20m
sec time
internal.
[Data
set
1]
[Data
set
1]
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