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noiana cxciusiw Hieaaayea
*
The
size
of the
requested data does not
indicate the
number
of bytes
that
will
make
up
a
DT!
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
Ijefore
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
hits
are zero
when
values
for
an
address,
size,
and
that
checksum
are
summed.
eData
set
1
:
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.
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.
•
Device
B
requesting data
from
Device
A
Device
B
sends an
SQl
message
to
Device A.
Checking
the
message. Device
A
sends a
DTI
message
back
to
Device
B.
DevicB
(A)
Device
(B)
[Data
set
I]
-^
[Request
data]
[Data
set
1]
*-
« More
than
20m
aao time
internal,
[Data
set
1]
^-
[Data
set
I]
'
'
—
^-
Byto
Description
FOH
Exclusive
41H
Manufacturer
10
(Roland)
DEV
Davica
ID
MDL
Model
ID
12H
Command
ID
aaH
Address
MSB
LSB
ddH
Da
a
sum
Ch
3ck
sum
F7H
End
ot
axduslve
*
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
tor
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 number
of bytes
comprising address data
varies
from one
Model-
10
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
*
Device
A
sending data
to
Device
B
Transfer
of a
DTI
message
is
all
that
takes
place.
Devtco
(A)
Device
CB)
[Data
set
1]
^-
« More
than
ZOm
aec time
internal-
EOata
set
I]
[Data
sat
1}
196
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