Since this is homework, it doesn't make sense for us to simply give you the answer, but we can try to guide you.

You say that you're studying program changes. What have you learned about it?

Cheers
Eddie

thanks for answer Eddie we are studying bn -cc-vv and F7 system exclusive if u can explain me I would be very grateful

Do you have the manual for the LS9, which, as far as I can tell, is a mixer.

Maybe, if you checked the manual, the answer might be there. Maybe your teacher is testing your ability to find the information in the manual (which I agree is often a MAJOR task).

I have no idea what is meant by '45 scene' in the context of a mixer. Is this something to do with 1945, or with 45 rpm single disks?

Also, bn -cc-w means nothing to me. Is this something specific to the LS9?

The LS9 may well be controllable by midi, possibly via SysEx (F7 etc) commands, but the commands may be fairly specialised and peculiar to the LS9.

Maybe, a proper and complete explanation of what you are wishing to do may help you onto the right path?

Geoff

thanks for answer Eddie we are studying bn -cc-vv and F7 system exclusive if u can explain me I would be very grateful

In brief, bn-cc-vv is a short MIDI message. "bn" is the status byte where "b" means "control change" and "n" represents a value from 0 to 15, which is the MIDI channel number. The "cc" is a value that represents which control is changing and the "vv" is a value from 0 to 127.

System exclusive messages are variable length messages that begin with F0h and end with F7h. These messages are more complex than short messages, but are very flexible. Many of them are manufacturer/model specific, but there are some standard system exclusive messages defined in the General MIDI specification, which you can find on this site.

Cheers
Eddie

but what how recall a scene ? my teacher show to us a example in logic pro but I did not understand 🙁

I realize there is a language barrier here, but what do you mean by "recall a scene"?

You originally mentioned that you were studying "program changes" so I suspect you're talking about "selecting an instrument" on a MIDI device. Correct?

Cheers
Eddie

Okay, looking at chapter 18 of the Yamaha LS9 user guide, it says that you can select a scene or effect library by sending a program change message to the LS9.

On page 180, the section "Using program changes to recall scenes and library items" discusses the concept in detail. Read through that section and let us know specifically what you are struggling to understand.

Cheers
Eddie

i dont understand how to write the message
we have to write in a piece of paper how is the message is

To understand this you will need to understand the structure of the MIDI message "Program Change".
At the very top of this page you will find a menu item "Specs" short for specifications.
Select this, then from the new list select "MIDI reference tables", then "Expanded Messages List".
(I suggest you bookmark that page.)
Scroll down this list and, about half way down you'll find the expanded form of the "Program Change" messages. They start with binary "1100".

The three formats shown in the first column show first, binary, second hexadecimal notation and last the decimal format. Hexadecimal (Hex) is the most commonly used, and it is often followed by an "H" to indicate that we're using this format. So the first byte might well be written as "C0H".

The second half of the byte denotes which MIDI channel the message is addressing.
So a message destined for what humans call channel 1 is encoded as 0.
We count 1 to 16, what is sent is 0 to 15. See the subsequent 15 messages in the table.

So a Program Change to MIDI channel 1 starts with the byte "C0H", for channel 2 "C1H", and so forth.

From the table we see that a Program Change is a two byte message.
The second byte is the program change number we want to transmit.
In your case 45. But remember, humans count, in this case, 1 to 128, but what is sent is 0 to 127.
So 45 would be ... what?

the scene 45

bulk. dump

Yes, the scene number (as understood by a human being) is 45, but how would that be represented as a hexadecimal number to be transmitted?

So, the first byte would be C0H. (Program change for channel 1).
The second byte would be what ... ??H.
Look how the channel number had to change from 1 to 0, so how is the scene number represented?
Then convert that decimal number to hex.

You'll need to understand this, because your lecturer may ask you how you arrived at the answer.
If you can't explain, he/she will know you don't understand, and ask where you got the answer from.
Believe me, I ask my students.

Hello.

I didn't post the answer here before because it was a homework for today. The class was this morning, so I can do it now.

The question was about System Exclusive. In particular the idea was to retrieve information about the Scene 45 in a LS9, not just to change the program. So,according to the manual, all you have to do is to send a Bulk Dump Request specifying the type of info that you want to receive.

In this case, it would be about scenes, so, in page 262, you can see right at the beggining of the page, the syntax of this bulk dump request, which is:

F0 43 2n 3E 12 mm ... mm dd dd F7

"n" Stands for the midi channel assigned to the given mixer. By default, this value would be 1, so we use 0 (n-1) in the corresponding byte. 43 means that we are talking about a YAMAHA device, 3E to a digital mixer, and 12 to the LS9. Then, mm ... mm are bytes that depend upon the task that you are involved in. In this case, we are talking about scenes. So, in the table that follows, you see this in the first row, labeled "SCENE LIB". The very next column is "SCENE___". This is a series of characters that you refer to in the chain by using their ascii codes, which are (in hex system) : 53 43 45 4E 45 5F 5F 5F . At first I thought that they left those 3 underscore characters to be filled with the number with the particular scene, but it turned out that it was only a way to complete 8 characters.

Last, for the "dd dd", there is the final column of the table, which has three notes: *1), *14) and *15).

If you read the respective notes, then you know that the first option gives you the information of a specific scene, the second of the currently selected one and the third is the same as the previous one, but including the recall safe settings. So, in the end, the list of hex numbers would be:

F0 43 20 3E 12 53 43 45 4E 45 5F 5F 5F 00 2D F7

Send this message to the LS9 and it will send you back the complete info about scene 45, including the name.

Homework done. 🙂