Roland TD-50 - Page 28

MIDI Implementation
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7Examples of Actual MIDI Messages
<Example 1> 92 3E 5F
9n is the Note-on status, and n is the MIDI channel number. Since 2H = 2, 3EH = 62,
and 5FH = 95, this is a Note-on message with MIDI CH = 3, note number 62 (note
name is D4), and velocity 95.
<Example 2> C9 20
CnH is the Program Change status, and n is the MIDI channel number. Since 9H = 9
and 20H = 32, this is a Program Change message with MIDI CH = 10, program number
33.
<Example 3> 99 2C 7F B9 04 7F 04 40
9n is the Note-on status, and n is the MIDI channel number. BnH is the Control
Change status, and n is the MIDI channel number. Thus, the above messages have the
following meaning.
99 2C 7F MIDI ch. 10, Note On message
B9 04 7F MIDI ch. 10, foot controller: 7FH
(B9) 04 40 (MIDI ch. 10), foot controller: 40H
In other words, with these messages a Note On message with a note number of
44 (G#2) and velocity of 127 is transmitted on MIDI Channel 10, and then the foot
controller value is set from 127 to 64.
According to the settings made at the factory, the drum part is assigned to MIDI
Channel 10, Note Number 44 is assigned to the pedal hi-hat, and the foot controller
is set to Pedal CC; in this case, the TD-50 plays a foot splash when the message is
received.
7How to calculate the checksum
(An “H” is appended to the end of numbers in hexadecimal notation.)
The checksum is a value derived by adding the address, data and checksum itself and
inverting the lower 7 bits.
Here’s an example of how the checksum is calculated. We will assume that in the
exclusive message we are transmitting, the address is aa bb cc ddH and the data is ee
 gg hhH.
aa + bb + cc + dd + ee +  + gg + hh = sum
sum / 128 = quotient ... remainder
128 - remainder = checksum
(However, the checksum will be 0 if the remainder is 0.)
<Example 1>
Specifying 3.5 as the shell depth of the instrument assigned to the snare head of
drum kit number 1
“Parameter address map” indicates that the start address of drum kit 1 is 04 00 00
00H, the oset address of the VEdit parameters of the instrument assigned to the
snare head is 01 01 00H, and the oset address of the shell depth (V-Edit Parameter 1)
is 00 01H; therefore, the address is
04 00 00 00H
01 01 00H
+) 00 01H
-------------------
04 01 01 01H
Since 3.5 is the parameter value 00 05H
F0 41 10 00 00 00 24 12 04 01 01 01 00 05 ?? F7
(1) (2) (3) (4) (5) address data checksum (6)
(1) Exclusive Status (2) ID (Roland)
(3) Device ID (17) (4) Model ID (TD-50)
(5) Command ID (DT1) (6) EOX
Then calculate the checksum.
04H + 01H + 01H + 01H + 00H + 05H = 4 + 1 + 1 + 1 + 0 + 5= 12 (sum)
12 (sum) ÷ 128 = 0 (quotient)… 12 (remainder) checksum = 128 - 12 (remainder) =
116 = 74H
This means that F0 41 10 00 00 00 24 12 04 01 01 01 00 05 74 F7 is the message
should be sent.
<Example 2>
Requesting transmission of the pad compressor switch for the snare of drum kit
number 1
“Parameter address map” indicates that the start address of drum kit 1 is 04 00 00
00H, the oset address of the snare pad parameters is 01 41 00H, and the oset
address of the pad compressor switch is 00 01H; therefore, the address is
04 00 00 00H
01 41 00H
+) 00 01H
-------------------
04 01 41 01H
Since the size is 00 00 00 01H
F0 41 10 00 00 00 24 11 04 01 41 01 00 00 00 01 ?? F7
(1) (2) (3) (4) (5) address data checksum (6)
(1) Exclusive Status (2) ID (Roland)
(3) Device ID (17) (4) Model ID (TD-50)
(5) Command ID (RQ1) (6) EOX
Then calculate the checksum.
04H + 01H + 41H + 01H + 00H + 00H + 00H + 01H = 4 + 1 + 65 + 1 + 0 + 0 + 0 + 1 =
72 (sum)
72 (sum) ÷ 128 = 0 (quotient)…72 (remainder) checksum = 128 - 72 (remainder) = 56
= 38H
This means that F0 41 10 00 00 00 24 11 04 01 41 01 00 00 00 01 38 F7 is the message
should be sent.