Rodgers PR-300S Owner's Manual page 146

•
I
.Checksum of Roland System Exclusive messages
Roland System Exclusive messages (RQI and DTI) have a Checksum at the end of the data (just before the EOX) to check for communication
errors.
The Checksum is determined by values of address and data (or size) included in the message.
<How to calculate Checksums> ("W indicates Hexadecimal.)
<Example I> Set "REVERB MACRO" to "ROOM 3"
The error checking process employs a sum-check error detection. It provides binary bit figures whose lower 7 bits are zero when values for an
address. data (or size) and the Checksum are summed.
According to the Parameter Address Map, the Address of REVERB MACRO is 40 01 30H, and the Value corresponding to ROOM 3 is 02H. So,
the message should be:
(
•
C
• •
(
(
• •
r
•
r
• •
• •
• •
(
('
• •
• •
• •
• •
, .
(
~
L
(4) Model ID (GS)
(5) Command ID (DTI)
(6) End of Exclusive
(4) Model ID (GS)
(5) Command ID (RQI)
(6) End of Exclusive
(4) Model ID (GS)
(5) Command ID (DTI)
(6) End of Exclusive
(I) Exclusive Status
(2) ID (Roland)
(3) Device ID (16)
(I) Exclusive Status
(2) ID (Roland)
(3) Device ID (16)
(I) Exclusive Status
(2) ID (Roland)
(3) DeviceID (16)
00 00 01 ?? F7
size checksum (6)
00 04 OE OA ??
F7
data checksum (6)
..Q.2... ?? F7
data checksum
(6)
FO
11. lQ
42
11
40 01 30
(I)
(2) (3) (4) (5) address
FO
11. lQ
42
11
41 00 00
(I) (2) (3) (4) (5) address
FO
11. lQ
42
11
41 02 4B
(I)
(2) (3) (4) (5) address
<Example 2> To request LEVEL of NOTE NUMBER 75 (0#5; Claves) in DRUM MAP I
The Checksum is:
40H + 0 I H + 30H + 02H =
64
+ I + 48 + 2 = 115 (sum)
115 (sum) % 128 = 0 (quotient) % 115 (remainder)
checksum = 128 - 115 (remainder) = 13 = ODH
Therefore. the message to send is : FO 41 10 42 12 40 01 30 02 00 F7
NOTE NUMBER 75 (0#5) is 4BH in Hexadecimal.
The Address of "LEVEL of NOTE NUMBER 75 (0#5; Claves) in DRUM MAP I" is 41 02 4BH, and the size is 00 00 01 H.
So. the message should be:
One practical equation to determine a Checksum is:
If the address is "ad bb ccH" and the data
(or
the size) is "dd ee ffH"
ad + bb + cc + dd + ee + ff = sum
sum % 128 = quotient % remainder
128 - remainder = checksum
The Checksum is:
41H + 02H + 4BH + OOH + OOH + OIH = 65 + 2 + 75
+
0
+ 0 + = 143 (sum)
143 (sum) % 128 = I (quotient) % 15 (remainder)
checksum = 128 - 15 (remainder) = 113 71 H
<Example 3> Set "MASTER TUNE" to +23.4 cents by System Exclusive.
The address of "MASTER TUNE" is 40 00 OOH. and the Size is 00 00 04H.
The Value should be nibblized data whose resolution is 0.1 cents, and which is a signed value ( 00 04 00 OOH (= 1024) = %0).
+23.4 [cents] = 234 + 1024 = 1258 = (hexadecimal)=> 04 EAH =(nibblized)=> 00 04 OE OAH
So. the message should be:
Therefore. the message to send is: FO 41 10 42 II 4! 02 4B 00 00 0 I 71 F7
The Checksum is :
41H + OOH + OOH + OOH + 04H + OEH + OAH = 65 + 0 + 0 + 0 + 4 + 14 + 10 = 93 (sum)
93 (sum) % 128 = 0 (quotient) % 93 (remainder)
checksum = 128 - 93 (remainder) = 35 = 23H
Therefore, the message to send is : FO 41 10 42 II 41 00 00 00 04 OE OA 23 F7
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