Roland R-8M Owner's Manual page 119

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