I suspect that the BK7-m is a Roland device, and this may be the device that makes the actual sounds you're interested in.
The A46 may be just a keyboard, and this may make the midi instruction to play a note.
If that IS the case, then you may need to do the opposite of what you ask about, and connect the midi OUT of the A46 to the midi IN of the BK7-m so that the midi instruction to play notes is transmitted to the BK7-m which will then play the sounds it has. You may need to pre-select the sound required on the BKM-7, or maybe you can set something via the S1/S2 buttons you refer to?
Try the pre-select first, then if that is working, try to get something more sophisticated?
The BK7m is indeed a Roland sound module. Finding sounds is no problem, I'm just trying to get the midi commands (numbers) from the Fast & Slow organ rotations (leslie) to the S1 and S2 buttons of the A49...
I still don't know much about what you're trying to do, as you're not telling us much.
I'll assume that there's no computer/software involved, else you'd have mentioned that!
I assume you've got the midi out on the A49 connected to the midi IN on the BK7.
You need the codes for the two controllers for Bank Select on the BK7, which may be Controller 0 (MSB) and Controller 32 (decimal) for LSB. These codes should be confirmed in the docs for the BK7, and the relevant values should be indicated. If the specific sound(s) you're trying to select are in the default sound set, then you may not need to use Bank Select, but I suspect you will need to use Bank Select. Also, as well as that, you will need to use a Program Change instruction, both the code for the instruction (incl the Channel to be used) and the code for the function, followed by the actual value (data) for the specific sound.
Not sure if you're trying to set up two separate sounds, one on S1 and the other on S2. This will depend on how many bytes of data you need, and how many bytes you can programme onto each key.
The midi data you need should be in the BK7 manual. The A49 manual should explain how to program the S1 and S2 keys.
If you try to do this, and it doesn't work, then please describe what you've done as per the suggestions above, and we may be able to explain where it's gone wrong.
First of all I assume you have the A49 MIDI Out socket connected to the MIDI In socket of the BK7-m using a standard MID Din cable?
But then I'm not sure that you can reprograme the S1 and S" keys to do exactly what you wish to, and here's why.
The normal function of S1 and S2, according to the page 10 of the A49 manual (A49_eng09_W.pdf) is to send a very simple Programme Change number Increment or Decrement message on each press. We'll come back to this manual shortly.
This function, as you've probably found out, effectively allows you to scroll through the various "voices" that the BK7-m has within it.
That would work fine for changing from Slow to Fast Rotary IF their voices were sequential in order in the BK7-m.
But they're not, even though they appear to be, being one after the other in the Tone List in the User Manual (page 91 of the BK7-m operation manual (BK7-m_OM.pdf)).
But if we look more closely we find the following:
Q. I'm assuming these mean Rotary Organ Slow and Fast and these are the two Tone settings you wish to change between?
This means that both voices use the same Programme Change number (PC=18) but use a different MIDI Bank Select MSB message (16 vs. 24) to change between them.
Both Slow and Fast Tones use Bank Select LSB (CC#32) set to 4 so it should not be necessary to change that.
So what you need is to be able to do is to reprogramme S1 and S2 to send CC#00=16 and CC#00=24 respectively.
If you now look at page 10 of the A49 manual, it points us to page 19,.
This then points us on to page 30/31 for reprogamming the function of S1 and S2. (Assigning a Control Change Number CC#).
This then refers us back to page 8 showing how to enter numbers using the keyboard and the Enter Key.
So, this seems to be telling us that we can set S1 to be CC#00 with a numeric value of 16 and set S2 to be a CC#00 with a numeric value of 24.
So far so good.
However, most Sound Modules (like the BK7-m) that I've used, require a Bank Select message (CC#00) to be followed by a Programme Change message before the Tone is actually changed within the device.
At the moment I can't see a way of getting either S1 or S2 to include a Programme Change message, after the CC#00 message, as well.
If you can follow so far then I suggest you experiment with what I've outlined so far and see whether you can get any further.
It may need the depression of a second key either on the A49 or the BK7-m to lock the Tone you want into place.
Meanwhile I'll take another look a the manual.
Hope that helps?
Roland BK-7m Backing Module manuals
Roland A-49 MIDI Keyboard Controller manuals
After thoroughly reading the manuals, I have the following ideas
Pre-recorded organ sounds
It sounds like the Roland BK-7m module might have some pre-recorded organ sounds that include variants with a fast and a slow rotary speaker sound. For those pre-recorded organ sounds, Control Change 16 might toggle between the fast or slow variation. (In the Roland BK-7m manual, page 54 mentions the "C1 parameter" which has a different effect depending on which sound is selected, for example, "it may [...] switch between the organ samples with the fast and slow rotary modulation [...]". Later on, page 68 mentions CC16 is a "general purpose controller that allows you to influence the C1 parameter".)
The Roland A-49 controller keyboard has buttons called S1 and S2 that can be programmed to send a Control Change message for any controller number 0 to 127, but they can only send a controller value of 127 or 0, either on press (127) and release (0), or on first press (127) and second press (0). In the Roland A-49 manual, page 31 explains how to set this up.
Try the following
To set up the S1 button to send Control Change 16 with a value of 127 on the first press and a value of 0 on the second press, press the following key sequence:
On the BK-7m, try selecting one of the organ sounds, perhaps "Rotary Organ", then see if pressing S1 on the A-49 changes the sound between a fast and slow rotary speaker sound.
The Roland BK-7m also appears to have audio effects (called "multi-effects" or "Mfx") that can create rotary speaker effects on any sound.
In the BK-7m manual, page 55 lists the Mfx types. I see three with "rotary" in the name:
Mfx type 9 is "Rotary"
Mfx type 57 is "VK Rotary"
Mfx type 83 is "Vib-Od-Rotary"
Pages 107 and following list the parameters available for each Mfx type. Each "rotary" type has an overall slow/fast speed parameter:
Mfx type 9 "Rotary" has a parameter called "Rotary Speed (Slow, Fast)"
Mfx type 57 "VK Rotary" has a parameter called "Speed (Slow, Fast)"
Mfx type 83 "Vib-Od-Rotary" has a parameter called "Rotary Speed (Slow, Fast)"
If you want to control one of these audio effect rotary speeds using a MIDI message, in the BK-7m MIDI Implementation document, pages 17 and onward seem to show that the Mfx effects can be set up with System Exclusive commands and then maybe certain functions assigned to Control Change messages (?), but the description is too brief for me to understand fully how they work, it would take some experimentation.
Be aware that the A-49 can't send System Exclusive messages, so it seems like this kind of control wouldn't be possible using only the A-49 by itself. Perhaps you would need to experiment with sending the System Exclusive messages from a computer to the BK-7m to see if you could eventually assign one of the slow/fast parameters to a Control Change message. Then perhaps you could assign that Control Change message to the A-49's S1 or S2 button.