Roland FC-200 - Manual (Page 39)

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1. Data Format for Exclusive Messages
Roland’s MIDI implementation uses the following data format for all
Exclusive messages (type IV):
Byte
F0H
41H
DEV
MDL
CMD
[BODY]
F7H
Description
Exclusive Status
Manufacturer ID (Roland)
Device ID
Model ID
Command ID
Main data
End of exclusive
•MIDI status: F0H, F7H
An Exclusive message must be flanked by a pair of status codes,
starting with a Manufacturer ID immediately after F0H (MIDI version
1.0).
•Manufacturer ID: 41H
The Manufacturer ID identifies the manufacturer of a MIDI instrument
that sends an Exclusive message. Value 41H represents Roland’s
Manufacturer ID.
•Device ID: DEV
The Device ID contains a unique value that identifies individual
devices in the implementation of several MIDI instruments. It is usually
set to 00H–0FH, a value smaller by one than that of a basic channel,
but value 00H–1FH may be used for a device with several basic
channels.
•Model ID: MDL
The Model ID contains a value that 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 00H in one or more places to provide
an extended data field. The following are examples of valid Model IDs,
each representing a unique model:
01H
02H
03H
00H, 01H
00H, 02H
00H, 00H, 01H
•Command ID: CMD
The Command ID indicates the function of an Exclusive message. The
Command ID format may contain 00H in one or more places to provide
an extended data field. The following are examples of valid Command
IDs, each representing a unique function:
01H
02H
03H
00H, 01H
00H, 02H
00H, 00H, 01H
•Main data: BODY
This field contains a message to be exchanged across an interface. The
exact data size and content will vary with the Model ID and Command
ID.
2. Address-mapped Data Transfer
Address mapping is a technique for transferring messages conforming
to the data format given in Section 1. It assigns a series of memory-
resident records—waveform and tone data, switch status, and param-
eters, 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.
•One-way transfer procedure (See Section 3 for
details.)
This procedure is suited to the transfer of a small amount of data. It
sends out an Exclusive message completely independent of the receiv-
ing device's status.
Connection Diagram
MIDI OUT
MIDI IN
MIDI IN
MIDI OUT
Device (A) Device (B)
1
2
Connection at point 2 is essential for “Request data” procedures. (See
Section 3.)
•Handshake-transfer procedure
(This device does not use this procedure)
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
MIDI OUT
MIDI IN
MIDI IN
MIDI OUT
Device (A) Device (B)
1
2
Connection at points 1 and 2 is essential.
Notes on the above 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.
ROLAND EXCLUSIVE MESSAGES