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Roland Exclusive Messages
*
'The size of the requested data dues not indicate the number of bytes
that will make up 2 DTI message, bui represents the address fieids
where the requested data resides.
+
Some
models are subject to limitations in data format used for e
single transaction,
Requested data, for example, may have a limit
ength or must be divided into predetermined address fields before
exchanged
&cross the interface.
e same number of byles comprises address and size data, which.
however, vary with the Model-ID.
*
The error 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.
=Data set 1: DT?
(12H)
This message corresponds to the actual dala transfer process,
Because every byte in the data |s 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 ime messages from interrupting an
excivsive one.
This fact is inconvenient
for the devices that suppan
a
"softthraugh"
mechanism. To maintain compatibility with such devices,
Roland
has limited the DTI
to 256 bytes so that an excessively long
ge is sent out in separate segments,
Byte
Description
FOH
Exclusive
41H
Manufacturer ID (Roland)
DEY
Device 10
MOL
Model ID
12H
Command ID
aH
Address MSB
use
ddh
Date
sum
Check sum
FTH
End of exclusive
* A DTI message is capable of providing only the valid data among
those specified by an RQI message.
*
Some models are subject to limitations in dala
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 Model
ID to another.
+ The error 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.
Example of Message Transactions
€ Device A sending data to Device B
Transfer of a DT! message js ali that takes place.
{Date set
1}
———————————»-
* More
than
20m
sec
time internal.
(Date set 1J
——————
{Data set 1)
——————
— —»-
9-— 28
'ice B requesting
data from
Device
A
Device
B sends
an RQI
message
ta Device
A.
Checking
the
message,
Device
A sends
a DTI
message
back
to Device
B.
Devica (4)
Device (B)
(Data set 1] Request
data]
[Data set 133. ———————————À—
* More than 20m sec time internal,
[Data set 1)
—————————
——b-
[Dats oat 1)
——amaeeiee i
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