Roland SK-50 Owner's Manual page 56

* The parameter number and the value of RPN or NRPN must be sent in correct order. As some sequencers may send those recorded data in
different order if an event is too close to another, it is recommended to place each event in a different tick. (1-tick for TPQN=92, or 5-ticks for
TPQN=480 is recommended.)
The send order may be different as each sequencer if the events are in the same clock in sequence data.
•Checksum of Roland System Exclusive messages
Roland System Exclusive messages (RQ1 and DT1) have a Checksum at the end of the data (just before EOX) to be able 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>
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.
One practical equation to determine 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
<Example 1> Set "REVERB MACRO" to "ROOM 3"
According to the Parameter Address Map, the Address of REVERB MACRO is 40 01 30H, and the Value correspond to ROOM 3 is
02H. So, the message should be :
F0 41 10 42
(1) (2) (3) (4) (5)
(1)Exclusive Status
(5)Command ID (DT1)
The Checksum is :
40H + 01H + 30H + 02H = 64 + 1 + 48 + 2 = 115(sum)
115(sum) ÷ 128 = 0(quotient) ... 115(remainder)
checksum = 128 - 115(remainder) = 13 = 0DH
Therefore, the message to send is : F0 41 10 42 12 40 01 30 02 0D F7
<Example 2> To request LEVEL of NOTE NUMBER 75(D#5; Claves) in DRUM MAP 1
NOTE NUMBER 75(D#5) is 4BH in Hexadecimal.
The Address of "LEVEL of NOTE NUMBER 75(D#5; Claves) in DRUM MAP 1" is 41 02 4BH, and the size is 00 00 01H.
So, the message should be :
F0 41 10 42 11 41 02 4B
(1) (2) (3) (4) (5)
(1)Exclusive Status
(5)Command ID (RQ1)
The Checksum is :
41H + 02H + 4BH + 00H + 00H + 01H = 65 + 2 + 75 + 0 + 0 + 1 = 143(sum)
143(sum) ÷ 128 = 1(quotient) ... 15(remainder)
checksum = 128 - 15(remainder) = 113 = 71H
Therefore, the message to send is : F0 41 10 42 11 41 02 4B 00 00 01 71 F7
<Example 3> Set "MASTER TUNE" to +23.4 cents by System Exclusive.
The Address of "MASTER TUNE" is 40 00 00H.
The Value should be nibblized data whose resolution is 0.1 cents, and which is a signed value ( 00 04 00 00H (= 1024) = ±0 ).
+23.4[cents] = 234 + 1024 = 1258 = 04 EAH = 00 04 0E 0AH (nibblized)
So, the message should be :
F0 41 10 42
(1) (2) (3) (4)
(1)Exclusive Status
(5)Command ID (DT1)
The Checksum is :
40H + 00H + 00H + 00H + 04H + 0EH + 0AH = 64 + 0 + 0 + 0 + 4 + 14 + 10 = 92(Sum)
92(sum) ÷ 128 = 0(quotient) ... 92(remainder)
checksum = 128 - 92(remainder) = 36 = 24H
Therefore, the message to send is : F0 41 10 42 12 40 00 00 00 04 0E 0A 24 F7
("H" indicates Hexadecimal.)
12 40 01 30 02 ??
address data checksum
(2)ID (Roland) (3)Device ID (16)
(6)End of Exclusive
00 00 01 ??
address size checksum
(2)ID (Roland) (3)Device ID (16)
(6)End of Exclusive
12 40 00 00 00 04 0E 0A
(5) address data
(2)ID (Roland) (3)Device ID (16)
(6)End of Exclusive
F7
(6)
(4)Model ID (GS)
F7
(6)
(4)Model ID (GS)
?? F7
checksum (6)
(4)Model ID (GS)
55