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%* The size of the requesied
daly docs net indicate fhe number
(8)
of bytes that
wit
make
up a DT}
message,
but
represents
the atldress fickls where the requested data resides.
[Data sev
1]
———————___—_____[Request
data]
*Soame
models
are subject
to fimilations
in data
format
used
for a single transaction,
Kequesicd
data, for example, may
[Data
set
1}
———————
have a limit in Jength or must
be divided
into predetermined
&More
than
20m
sec
time
internal.
address
fields before it is exchanged
across
the interface,
* The same
nuntber of bytes comprises address and size data,
[Data
Set
Vm
mennenineneriman ine
which, however,
vary with
the Model - JD.
:
* The
error checking
procuss
uses
a checksum
that provides
:
a bit pattern where the Icast
significant 7 bits are zero when
:
values
for an addre
# Data
set
1: DT1
(12H;
This
message corresponds
to the actual data
transfer
process.
4. | Handshake-.
Transfer
Procedure |
Because
every
byte in the data
i
ned a unique
address,
ze, and
that
checksum
are summed.
[Data
set
Vp
mie
a
DY]
message
can
wey
the
starting
address
of one
or
Handshaking
is
an
interactive
process
where
two
devices
more
data as well as a series of data formatted
in an address
exchange
error checking
signals
before a message
transaction
dependent
order.
lakes place, thereby increasing dala reliability, Unlike one-way
transfer
that
inserts
a
pause
between
message
transactions,
The
MIDI
standards
inhibit
non-real
time
messages
from
handshake
transfer allows
much
speedier transactions
because
interrupting an exclusive one,
This fact is inconvenient
for the
data
transfer
starts once
the receiving device returns a ready
devices that support a
"soft
through"
mechanism.
To maintain
signal,
compatibility with such dev
Roland
has fimiled the DT1
to
256 bytes so that an excessively
long message
is sent out in
When
it comes
to handling
large amounts
of data~
~ sampler
separate segments.
waveforms
and synthesizer lones over the entire range, for
example-—-across
u
MIDI
interface, handshaking
transfer
is
more
efficient
than
one-way
transfer,
Exclusive
Types
of Messages
Command
ID
M
f
e r
i
Raland
anufacturer
iD
(Roland)
Want
to send data
WSD (40H)
Device
ID
Modet
ID
Request
data
ROD
(43H)
Data
set
DAT
(42H)
Command
ID
Address
MSB
Acknowledge
ACK
(43H)
End of data
EOD (45H)
Communication
error
ERR (4EH)
ESB
Rejection
RUC (4FH)
Data
# Want to send data:
WSD
(40H)
This message
is sent out when
data must
be sent to a device
at the
other
end
of the
interface,
I contains
data
for the
address
and
size
that
specify
designation
and
length,
End
of exclusive
respectively, of the data
to be senl,
sateen
z
Check
sum
On
receiving
a
WSD
message,
the
remote
device
checks
its
*A
DT}
message
is capable of providing
only the valid data
memory
for
the
specified
data
address
and
size
which
will
among
those specified
by an
RQ?
message,
satisfy
the
request,
Hf
it
finds
them
and
is ready
for
*Some
models are subject to limitations in data
format
used
communication,
the
device
will
return
an
" Acknowledge
for a single transaction,
Requested
data, for example, may
{ACK)"
message.
have a limit in length or must
be divided
into predetermined
Otherwise, it will return
a "Rejection
(RIC)"
message.
address
fields before it is exchanged
across
the interface.
%*The number of bytes comprising address dala varies from
a
* The
error
checking
process
uses
a checksum
thal
provides
a bit pattern where the Icast significant
7 bits are zero when
values
for an address, size, and
Uhat
checksum
are summed.
Manufacturer
ID (Roland)
Device
1D
Exclusive
status
# Example
of Message
Transactions
Mode! IO
@Device
A sending data
to Device
B
Transfer of a DT{
message
is all that
takes
place.
Command
[D
Address
MSB
LSB
[Data
set
1}
——————————____
MSB
*More
than
20m
sec
time
internal.
'
(Data set 1}
————__-——————
LSB
:
Check
sum
:
End
of exclusive
{Data
sot
t]
ee
* The size of the dala to be sent does not indicate the number
@Device
B requesting
data
from
Device
A
of bytes
that
make
up
a "Datla
set
(DAT)"
message, but
Revice B sends an RQI
message
lo Device A.
Checking
the
represents
the address
ficlds where
the dala should
reside.
message, Device A sends
a IT}
message
back
to Device
B.
*Some
models
arc
subject
to limitations
in data
format
used
for a single
transaclion,
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
thal
provides
a bit pattern where
the least stnificant
7 bits are zero when
values
for an
address, size, and
chat checksum
are summed.
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