I got my answer: When I press RotarySP, the following is sent:

on/Fast:
10:13:48.156 From MIDI SysEx Yamaha 9 bytes F0 43 10 4C 03 01 02 01 F7

off/Slow:
10:13:48.897 From MIDI SysEx Yamaha 9 bytes F0 43 10 4C 03 01 02 00 F7

Now if I can get my controller to send this MIDI string . . . ?

My experience is that Yamaha only accepts input from influential insiders. They discount feedback from their rank-and-file customers, and don't readily admit it when they're wrong. They don't even document when they've changed certain things, perhaps for fear of being perceived that they got it wrong in the first place. That's my $.02, anyhow. [Edit: they have the arranger market in the U.S., and maybe the bulk of the broader keyboard market sewn up. If you walk into a music store in the U.S. all you see is Yamaha. So why should they change, or do anything to rock the boat?] Good luck!

Ted, for the most part, Yamaha HAS listened to it's customers, initiated many of the changes those customers requested, and had a large thread entitled "YAMAHA LISTENS" where consumers posted those requests.

When the displays went bad on the PSR-900, Yamaha stepped up to the plate and replaced the defective screens at no charge, even a year or more after the keyboard was out of warranty. When there was a software glitch, they came through with free upgrades and provided lots of user friendly instructions on how to install those upgrades. The list of things they changed that users requested is very extensive. I do not consider myself an influential insiders. However, I have had nothing but good experiences in dealing with Yamaha.

All the best,

Gary

Actually there is not a single Yamaha...

Yamaha US is their synth division
Yamaha EU is their arrangers and piano division

These divisions advice Yamaha Japan about features
And are in charge of the content (styles, arps, sounds)

Both parts work independantly..

Yamaha US now ha stheir own synth forum, where they discuss things with customers. And when you look at the Montage, Modx, the influence of the customers is huge..

Yamaha EU doesn’t directly communicate with customers. They only communicate trough their dealer network in EU. The problem is these dealers have a whole different idea about arrangers then a part of the customers..


And then there is Yamaha Japan, that wants as few crossovers between different types of products as possible.. they are kind of the guardians of the development traject. The western divisions acknowledge communication with Japan is rough.


The company is very traditional and conservative, choosing quallity above innovation. Just ask yourself how much has a grandpiano changed over the last century? Then take this attitude and project it on keyboards..


Anyway, back to Yamaha EU, their designs are still mostly based on a stand alone can do it all design. Thats why certain things dont get the attention they needs (midi, integration with other hardware and software products is one of them) ... but also keep in mind that the majority of users doesnt really care about these kind of things.. so the dealers dont push them... Whenever you go to a yamaha dealer presentation and look around for the typical Yamaha customer, you will notice..
Yamaha US has no influence or part in the arranger design.. same goes for Yamaha EU and the synth part.. thats one of the reaons why i think the arrangers feel somewhat alienated in the US. In most european music shops they are still the central part of the shop..