Roland HP 3700 Owner's Manual page 22

20
Roland Exclusive Messages
ff data Format for Exclusive Messages
Roland's MIDI implementation uses the following data format for alt
exclusive messages (type IV):
FOH Exclusive status
41H Manufacturer ID (Roland)
DEV Device ID
MDL Model ID
CMD
(BODY}
F7H End of exclusive
Command {D
Main data
# MIDI status: FOH, F7H
An exclusive message must be flanked by a pair of slatus codes, starting
with a Manufacturer-ID immediately after FOH (MIDI version1.0).
#Manufacturer|D: 41H
The Manufacturer-ID identifies the manufacturer of a MIDI instrument
that triggers an exclusive message. Value 41H represents Roland's
Manufacturer-ID.
#Device-ID: DEV
The Device-ID contains a unique vaiue that identifies the individual device
in the multiple implementation of MIDI instruments. It is usually set to
OOH ~- OFH, a value smaller by one than that of a basic channel, but
value OOH ~ 1FH may be used for a device with multiple basic channels.
#Model.lD: MDL
The ModeliD contains a value that uniquely identifies one model from
another. Different models, however, may share an identical Model-ID if
they handle similar data.
The Model-ID format may contain OOH in one or more places to provide
an extended data field. The following are examples of valid Model-IDs,
each representing a unique model:
Ol
02H
03H
OOH, 01H
OOH, 02H
OOH, OOH, 01H
+CommandID; CMD
The Command-ID indicates the function of an exclusive message. The
Command.ID format may contain OOH in one or more places to provide
an extended data field. The following are examples of valid Command-
IDs, each representing a unique function :
O1H
02H
03H
OOH, 01H
OOH, 02H
OOH, OOH, O1H
# Main data: BODY
This field contains a message to be exchanged across an interface.
The exact data size and contents will vary with the Model-ID and
Command ID.
yaa Address.mapped Data Transfer
Address mapping is a technique for transferring messages conforming
to the data format given in Section 1. [t assigns a series of memory-
resident records-waveform and tone data, switch status, and parameters,
for example-to specific locations in a machine-dependent address space,
thereby allowing access to data residing at the address a message
specifies.
Address-mapped data transfer is therefore independent of models and
data categories. This technique allows use of two different transfer
procedures: one-way transfer and handshake transfer.
3 One-way transfer procedure (See Section 3 for details.)
This procedure is suited for the transfer of a small amount of data.
It sends out an exclusive message completely independent of a receiving
device status,
Connection Diagram
Device (A) Device (B}
Connection at point 2 is essential for "Request data" procedures. (See
Section 3.)
xHandshake-transfer procedure (See Section 4 for details.)
This procedure initiates a predetermined transfer sequence (handshaking)
across the interface before data transfer takes place. Handshaking ensures
that reliability and transfer speed are high enough to handle a large
amount of data.
Connection Diagram
Device (A)
Device (B)
Connection at points { and 2 is essential.
Notes on the above two procedures
%* There are separate Command-IDs for different transfer procedures.
* Devices A and B cannot exchange data unless they use the same
transfer procedure, share identical Device-ID and Model ID, and are
ready for communication.
cas One-way Transfer Procedure
This procedure sends out data all the way until it stops and is used
when the messages are so short that answerbacks need not be checked.
For long messages, however, the receiving device must acquire each
message in time with the transfer sequence, which inserts intervals of
at least 20 milliseconds in between.
Types of Messages
RQ! (11H)
DT1 (12H)
Request data 1!
Data set |
#Request data +1: RQ1 (11H)
This message is sent out when there is a need to acquire data from
a device at the other end of the interface. It contains data for the address
and size tha! specify designation and length, respectively, of dala required.
On receiving an RQi message, the remote device checks its memory for
the data address and size that satisfy the request.
If it finds them and is ready for communication, the device will transmit
a "Data set 1 (DT1)" message, which contains the requested dala.
Otherwise, the device will send out nothing.
Exclusive status
Manufacturer ID (Roland)
Device iD
Mode! ID
Command ID
Address MSB
LSB
MSB
LSB
Check sum
End of exclusive