Roland Exclusive Messages
= Data set 1
*The size ot
the requested data does not indicate the
numlier
of bytes (hat
will make up a DTI messase, but
represents
(he
address fields where the
requested data resides.
*Some models are subject to
1imi(a(ions in data format used
for a single transaction.
Requested data, for examine, may
have a limit in length or must be
divided into predetermined
address fields before it is
exchanged across the interface.
*The same
numl)^
or
bytes comprises address and ^ze
data,
which,
however, vary with the Model-ID.
«The error checking process uses a checksum
that provides
a bit pattern
where
the
least sisnificant 7 bits are zero
when
values for an address, size, and
that checksum are summed.
DTI
c12H)
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. Tl>is 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
(hat an excessively k>ng message is sent out in
separate segments.
8yt«
Description
FOH Exclusiva
&\H
Manufacturer
ID (Roland)
DEV Device ID
MOL Model ID
12H Command ID
aaH Address MSB
LSB
ddH Da a
sum Ch ick sum
F7H
End of exclusive
*A DTI message is
capable
of
providing
only (he
valid
dala
among those
specified by an RQl
message.
i^Some
models are subject (o
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 number of
bytes comprising
address data
varies from
one ModeHD
to anothw.
*The error checking process uses a checksum (hat
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 (o
Device
B
Transfer of a DTI message is all that lakes place.
#Device B requcsiing 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 (a7|
[Date set Ij
-^
[Oats set 1]
»-
* Mora than 20m sec time
internal.
[Data set I]
:
^-
[Data set 1]
'
-
I
Device
(6)
[
-[Request daia]
I Handshake-Transfer Procedure
Handshatiing
is an
interactive process whea< two
devices
exdiange error checking
signals
.before
a message irdnsaction
takes
place, thereby
increa^ng data reliability. L'nIiKe
iinenn)'
transfer that inserts a pause
between
message
ironsut; lions,
handshake transfer
allows
much speedier
(ransaciions buciusi.'
data transfer starts once (he
receiving device returns
a reody
signal
When
i( comes (o handling large amounts of
data-sami)ii.'r
waveforms artd syn[hesizer (ones over the entire range, for
example-across a MIDI interface, handshaking transfer is inure
effident than one-way transfer.
Types of Messages
Message
Command
ID
Want
to
send
data
WSD C-JOH)
Request data ROD (41 H>
Data set
OAT Cd2H)
Acknowledge ACK (43H)
End of daia EOD
(dSH)
Communication error ERR (4EH>
Rejection RJC (4FH)
4 Want to send data : WSD (40H)
This message is sent out
when
data must be sent lo a
device
at the other end of the interface. It
contains
data
for
ihe
address
and size that
specify designation and it-ngih
.
respectively,
of the data lo bn
sent.
On receiving
a
WSD message, (he remote device checks its
memory for the specified dala
address and size \vhich win
satisfy
the request. H it
finds ihem and is
ready
tor
communication, the device will return an "Acknowledge
(ACK)" message.
I
DBviee (A)
I I
Device
(8)
|
[Data set IJ
^-
* More than 20m sec time internal.
[Data
set
IJ
:
^
(Data set 1]
Byte Description
FOH
Exclusive
status
4)H
Manufacturer ID (Roland)
OEV
Device ID
MDL
Model 10
40H Command ID
aaH Address MSB
LSB
SSH Size
MSB
LSB
sum Check
sum
F7H End of exclusive
Otherwise,
it will return a 'Rejection (RJC)" message.
*The size of (he data to be sent docs noi
indicate
(he number
of bytes that make up a "Data set (DAT)" message,
iiui
represents (he
address fiekls where the data should reside.
*Some models are subject to limitations in data tornm used
for a
single iransaction. Requested data, for example, may
have
a limit in
length or must t>e
divided
into prcdcicmiincd
address fields before it is exchanged across the intcrracc.
*The same numtxr of
bytes comprises address and size
da(a.
which,
however,
vary with
(he
ModellD.
*The error
checking
process uses
a checksum ihai provides
a bit paiiem
where
(he
(easi significani 7 biis
are «;ro
when
values
for an address, sizo, and thai checksum
are sunmied.
117
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