Arpeggios aren't setup to that. At least not one arpeggio that would work like that.

You could perhaps create fixed arpeggio types where there are multiple arpeggios and each one is a different quality (major, minor, 7th, etc) and then Part 1 covers the range of C1 and uses the major ARP type. Part 2 covers the range of C2 and uses the minor ARP type. Etc ...

The way ARPs do work is you could play a minor triad and the ARP notes will fit that quality. Or play a major triad and the ARP would modify to fit that quality ... and so on.

This isn't what you want - but that's the way it works.

I think this is what I need.
True, I did not notice the difference.
I don't know the instrument well.
It is necessary to check how this can be done.

Thank you!

Where can I specify chords? Maj, min... How to it'll assign or it records?

You would record the full chord.

1. applicature: full chord (maj or min)
2. midi data: one tone repeat C, C, C...
Arp don't need contains all tones... Something I not understand 🙂

Use the fixed arpeggio type.

This would lock down the notes to just say a Cmaj for one Part where the chord couldn't be moved around (transposed) if you played say a D1 instead of C1. Which may or may not be what you want.

1. Please help! Tell me there is a way from pedal or ModWheel to change on the fly octave or current arpeggio-preset?
To set octave up or down, or set arp preset1 to preset2.
The panel buttons octave are too hard, hands are busy and would like to pedal.

2. Is it possible to assign the layers of velocity to the modwheel? For example to switch some megavoice layers.

I have an old message where I wished I could "steer" velocity using controllers. I had different applications not so much related to ARPs - but in order to have better control over articulations than XA control would give. These options to force notes to specific velocities are not there since parameters to affect velocity (like velocity offset, etc) cannot be destinations in the control matrix.

If you wanted to do this with something like the modwheel I would suggest going a different route - only because the route you and I both desire is not available - not because it's a "great" solution. What you'll have to do is setup a separate Part for each "velocity layer". For each voice you can set the ARP or create one that is playing at the desired velocity to play whichever velocity level you're targeting. Then morph (or hard-cut) between the different Parts to bring out the velocities you want. Basically, I'm saying here is replicate the Part over and over and have the arpeggio for each Part set the velocity to a fixed velocity you're targeting. Then "select" the velocity you're after by turning the level up on the Part that matches the velocity you're after.

And you can extend this to select a particular Arpeggio preset. Again - you would use the idea of replicating the Part to another. On the 2nd Part you would have the different arpeggio (in the same slot - say slot 1) and you would be changing arpeggios by bringing up the level on the Part with the associated arpeggio you want to be playing. The downside to this approach is that it eats up polyphony. Because even the parts with the level down will be consuming polyphony.

The other thing you could do is setup your scenes 1-8 to vary the arpeggio then use a pedal to modulate the scene # according to the scene CC. I'd have to setup my keyboard to see if this can be done without a MIDI pedal. Sometimes you can set one controller to a CC that matches another and it will control the other function. Like footswitch and A.SW1/A.SW2. You can set the footswitch to the same CC as either of these buttons then pressing the footswitch will turn on/off the associated button. There are some cases where this cannot be done I haven't memorized it. However - in all cases you can get a MIDI pedal that can be set to the Scene CC# in order to use a pedal sweep to select scene # 1-8. It may be easier, however, to use a pedal board that provides a foot switch for every scene# where you can have more direct control over the scene switches with your foot. It's not so easy to select a particular scene using a foot pedal (heel to toe type aka expression pedal).

You can't change the octave (as in trigger a different note) using the mod wheel. Unfortunately note shift is not a target parameter. You can change the pitch by stretching the pitch. This may be sufficient. You can try to approximate the amount of pitch shift in order to stretch up (or down) a couple octaves. It's going to affect the timbre of the sound. Use the destination as "pitch" and change the curve to a square such that part of the modwheel sweep is no offset part (maybe 1/2) has the offset you're after.

My task is that I have ready chords samples. Left hand of the accordion. Ready audio triads for each key.
C1-B1 ostinato basses
C2-B2 Major triads (c-e-g) (c#-e#-g#) etc.
C3-B3 minor triads
C4-B4 7-th triads (c-e-b♭‎)
C5-B5 dim triads (a-c-e♭‎)
Ready chords sound more realistic. And I have yet guitar strum sliced chords above

You haven't quite explained the task although I have a good idea of how your keyboard is split.