;;:
Request
data:
RQO
(41
H)
ThIs message
Is
sent out when there
Is
a need to acquire
data
from a devIce
at
the
other
end of the interlace.
It
contains data
for the
address and size that specify designation and length.
respectively, of data required.
On receiving
an
RQD
message. the remote device checks Its
memory
for
the dala address
and
size which satisfy the requesL
If
It
finds them and
is
ready for communication.
the
device
wUl
transmit a
~Dala
set
(DAT'~
message, which conlains the
requested data. Otherwise, it
will
retum
a
~ReJection
(RJe,"
message.
Byte
DescriPtion
FOH
Ellclusive
stfltus
41H
Manufflcturer
tD
(Rolend)
DEV
Device
10
MDL
Model
10
41H Commend
ID
"H
Address
MSa
LSa
"H
Size
MSa
LSB
.om
Check
.em
F7H End
of
exclusivB
*The
size
of
the requested data does not indicate the number
of
o),les that make up a
~nata
set
(OAT)
~
message, out
represents the address fields where the requested data
resides.
*Some
models are suoject to limitations
in
data format used
for a single transaction. Requested data. for example, may
have a
limJt
in
length
or
must be divided into predetermined
address fields before
it
is exchanged across the interface.
*The
same number
of
hytes comprises address and size data.
which. however. vary
with the
Model
- 10.
*The
error checking process uses a checksum that provides
a bit
pattern where the least signlficanL 7 bits
are
zero when
values (or an address,
siZe.
and that checksum
are
summed.
;-
Data
set:
DAT (42H)
This message corresponds
to
the actual dala transfer process,
Because every
byte
in
the data
is
assigned a unique address,
the message
can
convey the slarting address
ot
one
or
more
data
as
well
as
a series of data formatted
in
an
address-
dependent order.
Although the
MIDI
standards inhibit non - real time messages
from
interrupting an exclusive one, some devices support a
"soft -
lhrough~
mechanism for such interrupts. To maintain
compatibility with
such devices, Roland has limited the OAT to
256
bytes so that an excessively long message
is
sent out
in
separate segments.
Byte Description
FOH
Exclusive
status
41H
Manufacturer
ID
(Roland)
DEV Device
10
MDL Modal
10
42H
Commend ID
..
H
Address
MSa
LSa
ddH
Dar
"rn
Check
,urn
F7H
End at e)(cluslv"
*A
OAT message
Is
capable
of
providing only the valid data
among
those specified by
an
RQD
or
WSD
message.
"'Some models
are
subject
lo
Iimilations in data format used
for a single transaction. Requested data, for example, may
have a !lmit
In
length
or
must be divided into predetermined
address fields before It
Is
exchanged across
thB
interface.
*The
number ot bytes comprising address data varies from
one model
ID
to another.
* The en'Ol' 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.
.:j':
Acknowledge:
ACK
(43H)
This message
is
sent
out when no
error
was
detected
on
recept!on of a
WSD,
DAT,
~End
of data (EOD)",
or
some other
message and a
requested setup
or
action is complete. Unless
it
receives an
ACK
message. the device
at
the
other
end
will
not proceed
to
the next operat!on.
Byte Description
FOH
Exclusive stStUS
41H
Manufacturer
ID (Roland)
DEV Device
10
MDL
Model
lD
43H
Commend ID
PH
End of exclUSive
:::
End
of
data:
EOD
(45H)
This message is sent out
to
inform a
rem01,e
device
of
the end
of
a message. Communication, however,
will
not come to an
end unless the
remote device
retums
an
ACK
message even
though
an
EOn message was transmitted.
By<.
Description
FOH
Exclusive
status
41H
Manufacturer
ID (Roland)
DEV Device
ID
MDL
Model
10
45H
Command ID
F7H End of axclus',ve
~
Communications
error:
ERR
(4EH)
This message warns the remote device
of
a communications
fault
enwuntered during message transmission
due,
for
example.
to
a checksum error. An
ERR
message may
be
replaced with a
~Rejection
(rue)
~
one.
Which
terminates the
current message transaction
in midstream.
When
it
receives an
ERR
message, the sending device may
either altempt
to
send out the last message a second time
or
terminate communication hy sending out an
RIC
message.
Byte
Description
FO,,",
Exclusive
status
41H
Menufacturer
ID (Roland)
DEV Device
10
MDL
Model
iO
4EH
Command
ID
F7H
End
of
e)(clusive
23
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