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        MIDI-OX >> Questions and Discussion >> sysex and MIDI question
        
(Message started by: hackwojr on Jul 15^th, 2004, 8:51pm)

Title: sysex and MIDI question
Post by hackwojr on Jul 15^th, 2004, 8:51pm

Hello,

I have used MIDI for years but have never tried to figure out sysex because I haven't needed to. Now I own a keyboard with some great effects that can only be accessed with sysex messages. I have tried tech manuals and internet stuff, but it usually is much to indepth. The article about NRPN on these pages is good, but again not enough and assumes I know some things I don't.

What I need is a good book that describes sysex (not a basic MIDI book because they say little about sysex.)

Does anyone know of a good book that can explain this perplexing topic? How did you all learn about Sysex?

Thanks,
jeremy

Title: Re: sysex and MIDI question
Post by Peter L Jones on Jul 16^th, 2004, 3:24pm

Mmm, that's a good question in itself... I usually have MIDI docs for everything.

But SysEx is different.

A SysEx sequence is
F0 xx xx xx F7
where the xx xx xx can be any data bytes you like. The meaning of the bit between F0 and F7 is entirely system dependent (hence, System Exclusive -> SysEx). The first few bytes of the data, however, are controlled by the MIDI Manufacturers Association to enable a device to confirm a SysEx sequence is intended for it (i.e. contains an ID sequence).

The best I can dig up is a couple of examples.

There's a page about Roland's SysEx implementation which covers why the thing was created in the first place and how Roland implement it:
http://www.borg.com/~jglatt/tutr/rolsysx.htm
I would guess that's pretty much how many other manufacturers chose to do it...

But take a look at this - the Sample Dump Standard:
http://www.borg.com/~jglatt/tech/sds.htm
for an alternative way of using SysEx.

I'm sure there's more around stuff around, too.

Title: Re: sysex and MIDI question
Post by Jamie OConnell on Jul 17^th, 2004, 11:32am

It would be difficult to do a book soley on the topic of SysEx because it is completely free-form and up to each manufacturer on how to implement it.

The only rules about SysEx come from the official MIDI 1.0 spec., which basically states that a SysEx message must begin with a (hex) F0 and end with a F7. Following the F0 is either a manufacturer ID or the 'universal sysex' identifier (7E, 7F), and there are only a few universal messages defined. Everything else is completely up to the manufacturer, and every manufacturer handles things differently.

Title: Re: sysex and MIDI question
Post by hackwojr on Jul 17^th, 2004, 8:33pm

Peter, Thanks for the information links. They were helpful and I certainly have a much greater handle and understanding of how Roland does things, and even more understanding or SysEx. The checksum is confusing since I haven't done division with remainders since 3rd grade.

Jamie, you are very correct. I understood the posted articles, but when I look in my yamaha psr manual, it seems completely greek to me. As you said, different companies do things different - so you would think they could explain their ways. However, I asked yamaha just this - to try to explain their SysEx in the manual, or if they have any tech documents or postings about the subject - and the reply was -- "you need to buy a book on MIDI and read about SysEx." - thus my question here, and that of course completes the circle.

jeremy