Roland V-Mixer VM-7200 Manual Del Usuario página 72

MIDI Implementado
Example of system exclusive message and Checksum
calculation
On Roland system exclusive message (DT1), checksum is added at the end of transmitted
data (in front of F7) to check the message is received correctly. Value of checksum is defined
by address and data (or size) of the system exclusive message to be transmitted.
How to calculate checksum (Hexadecimal number is shown with H.)
Checksum is a value which lower 7 bit of the sum of address, size and checksum itself turns
to be 0.
If the address of the system exclusive message to be transmitted is aa bb ccH and data or
size is dd ee ffH,
aa + bb + cc + dd + ee + ff = sum
sum / 128 = quotient and odd
When odd is 0, 0 = checksum
When odd is other than 0, 128 - odd = checksum
MIDI Machine Control (MMC) Command,
Information field / Response Reference
Command Recognized
Command Action
01H STOP STOP
02H PLAY PLAY
03H DEFERRED PLAY PLAY
04H FAST FORWARD FF
05H REWIND REW
06H RECORD STROBE REC / PUNCH IN
07H RECORD EXIT PUNCH OUT
0DH MMC RESET RESET
40H WRITE Write Information Fields
41H MASKED WRITE Set Track Status Information Fields
44H 00H LOCATE I/F LOCATE (Read locator)
44H 01H LOCATE TARGET LOCATE (Designated Time)
4CH MOVE Move between Information Fields
Commands Transmitted
Command Action
01H STOP STOP
03H DEFERRED PLAY PLAY
04H FAST FORWARD FF
05H REWIND REW
06H RECORD STROBE REC / PUNCH IN
07H RECORD EXIT PUNCH OUT
0DH MMC RESET RESET
44H 01H LOCATE TARGET LOCATE
Valid Information Fields / Response
Information Field Interpret
01H SELECTED TIME CODE Current Time
08H GP0 / LOCATE POINT Locator 1
09H GP1 Locator 2
0AH GP2 Locator 3
0BH GP3 Locator 4
0CH GP4 Locator 5
0DH GP5 Locator 6
0EH GP6 Locator 7
0FH GP7 Locator 8
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Valid Commands
MOVE(FROM)
MOVE(FROM), MOVE(TO), WRITE
MOVE (FROM), MOVE (TO), WRITE
MOVE (FROM), MOVE (TO), WRITE
MOVE (FROM), MOVE (TO), WRITE
MOVE (FROM), MOVE (TO), WRITE
MOVE (FROM), MOVE (TO), WRITE
MOVE (FROM), MOVE (TO), WRITE
MOVE (FROM), MOVE (TO), WRITE