Table of Contents
Advertisement
# Request data
# Data set:
ROD
(41H)
This message is seni aut when there is a need to acquire data
from a device at ihe other end af the interface.
It contains data
for the address and size thal specify designation and length,
respectively, of data
required.
On
receiving
an RQD
message, the
remole
device checks its
memory for ihe daia address and size which salisfy the request.
If it finds them and is ready for cammunication, the device will
transmit
a "Data
set
(DAT)"
message,
which
contains
the
requesied data, Otherwise, it will return a "Rejection
(RJC)"
message,
Byte
Description
1.08
FOH
Exciusive
status
aH
Manutacturer ID (Roland)
DEV
Device 10
MDL
Mode!
ID
41H
Command
10
eH
Address MSB
:
LSB
ssH
Size
MSB
'
LSB
sum
Check
sum
FTH
End of exclusive
The
size of the requested data does not indicate the number
of bytes thal make up # "Data set
(DAT)"
message, but
represents
the address
fields
where
the requested
data
resides.
Some
models are subject to limitations in data format used
for o 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 same number of bytes comprises address and size data,
which, however, vary with the Madel—ID.
%*The error checking process uses a checksum thal provides
a bit pallern where the least significant 7 bits are zero when
values Jor an address, size, and that checksum are summed,
DAT
(42H)
'This message corresponds to the actual data transfer process.
Because every byte in the data {s assigned a unique address,
the message can convey the starting address of one or more
data
as
well
as
a
series
of
data
formatted
in
an
address—dependent order.
Although the MID] slandards inhibit non-real time messages
from interrupting an exclusive one, some devices support a "
soft~ through "
mechanism
for
such
interrupts.
To
maintaincompatibility
with such devices, Roland has limited the
DAT
to 256bytes so that an excessively long message
is sent
oul in separate
segments,
Byte
Description
FOH
Exclusive
status
43H
Manufacturer 1D (Roland)
DEV
Device iD
MDL
Model
ID
42H
Command 1D
aaH
Address
MSB
LsB
edH
Data
sum
Check sum
F7K
End of exclusive
# Acknowledge :
#End of data:
%*A DAT
message
is capable af providing only the valid data
amoung those specified by an RQD or WSID message.
Some
models ure subject to fimilalions in data formal used
for a single transaction.
Requested duta, for example, may
have a limil in length or must be divided into predetermined
address
fields before it is exchanged across the interlace.
The
number
of bytes comprising
address
data varies {rom
one
mode!
II) to ancther,
ACK
(43H)
Byte
Oescription
FOH
Exclusive status
41H
Manufacturer ID (Roland)
DEV
Device ID
MDL
Model {D
43H
Command
iD
F7H
End of exclusive
EOD
(45H)
This message is sent out to inform a remote device of the end
of a message.
Communication, however, will not came
to an
end
unless the remote device relurns an ACK message even
though an
EOD message was transmitted.
Exclusive status
Manufacturer ID (Roland)
Device
ID
Model
ID
Command
!D
End of exclusive
# Communications
error;
ERR
(4EH)
'This message warns the remole device of a communications
fault
encountered
during
message
transmission
due,
far
example, to a checksum
error,
An ERR
message
may
be
replaced with a "Rejection
(RIC)"
one, which terminates the
current message transaction in midstream,
When
it receives
an
ERR
message,
the sending
device may
either
aliempt
lo send
out
the fast message
a second
time
or
terminate communication by sending out an RIC message.
Byte
Description
FORK
Exclusive
status
4iH
Manufacturer ID (Roland)
OEV
Device
ID
MOL
Medel
1D
4EH
Command
ID
F7H
End of exciusive
Advertisement
Table of Contents
