Usually the sysex documentation explains for each command what the variables stand for [the letters are just variables to be replaced by a hexadecimal value]. This is so obvious that it always assumed and people who can't figure that out shouldn't bother trying. Hexadecimal is 0 to F [not H].
The pairing of the letters means that they represent an 8 bit value (two hex nibbles). Often the letters are used to have some kind of significance.
In the case of the note on command (which is strictly speaking NOT sysex), 8n means that the hexadecimal nibble pair with an 8 as the first nibble and 'n' as the second (for the midi channel); kk represents the note [a bigger number is a higher pitched note]; and vv represents the velocity [a bigger number is a louder note & a velocity of 00 is the same as note off]. The note on command is one way of switching notes off, but there is also a separate note off command. Sysex is used for more complex things than switching notes on and off.
It seems that you do not have the background to work with sysex, so you should probably give up.
From: Rob
To: xl7@yahoogroups.com
Sent: Tue, February 23, 2010 11:31:36 AM
Subject: [xl7] Newbie: understanding Hex & SysEx??????????????
To: xl7@yahoogroups.com
Sent: Tue, February 23, 2010 11:31:36 AM
Subject: [xl7] Newbie: understanding Hex & SysEx??????????????
I've only been producing and using the Emu a few months. I've been reading manuals and everything on the internet I can find. I am starting to understand Hex & have figure out NRPNs and CC. BUT some SysEx is alien to me. The Emu manual has things like KK VV XX YY ZZ NN but hex is 0 to H. The sysex info seems to have different meanings for different commands for the letters.
8n kk vv is the command for note off.
n = midi number
kk = ?
vv = ?
Is this so standard that all companies shouldn't have to define it and I'm missing some chart on it?
Is 8n kk vv all I enter or do I need more numbers for machine ID, EMU id, on, off, etc?
Most of the tutorial sites treat you like a computer programer not a layman.