No. Arpeggios can be started, by definition, in one manner = by triggering (touching) the keyboard.
It is not a sequence, so a start button does not mean anything to an arpeggio. It is always started by touching the keyboard.

What would it play when you pressed start? It's a rhetorical question because it does not have an answer (how about Eb7#9?) 🙂

Conditions for ARPEGGIO use
The Master ARP ON/OFF button must be ON
The PART ARP ON/OFF button must be ON
And you must trigger a KEY on the keyboard within the ARP NoteLimit range for the arpeggio to start. Those are your parameters.
A "start/play" button would not apply.

What you have on offer
When you have a Drum ARP set to play, you can have it stop by programming one of the eight locations for ARP SELECT to act as a "musical rest". This is referred to in your ARPEGGIO LIST as a "MUTE" Arp... "MUTE 4/4", for example, would have the Drum Part Stop for however long you require but the timing count in 4/4 time. You will find MUTE ARPs in various time signatures at the very end of the arpeggio list. There is no note data (no events) in the MUTE Arp; it is just a placeholder so that the drummer is tacit, until you hit the next ARP SELECT button which will have an Arpeggio phrase linked to it.

This you can do, because the ARP is still set to HOLD, it just is tacit (lays out, does not sound) but comes back in time, on demand, by pressing the ARP SELECT button which contains a drum phrase. Make sense?

It's "MUTE", again, you want MUTE function, not a Start/Play button for arpeggio(sic), which is not possible, by definition.
"Mute". Perhaps a word that does not translate well. But it allows the time (count) to continue, yet the drummer has stopped playing. the drums come back, in time, when you select the next ARP SELECT.

A MUTE arp is better than leaving the ARP SELECT position empty, because that just STOPS the drums all together. But MUTE allows you to bring the Drummer back in, and ON TIME, because the MUTE ARP will count (if you select the right time signature). I'm hoping that translates well.

Bad Mister thanks for reply but my problem is not solved. I need something that can restart the drum arpeggio by one touch. That's very common in a drum machine for example. Why I need it? Because if my guitar man loose the time of the drum and go straight for his way time, I can immediately sincronyze new starting to the right time of guitarist. It happens. I had a boss 880 drum machine and this function was very appreciated by me. Now that I sell all my old instrument to buy montage, sometime I can't find this kind of fast and very efficient things.
Best regards

I guess it's the language barrier. Let's try again...
Your boss 880 drum machine did *not* have an arpeggiator. We are talking here about the Arpeggiator, right? It cannot just start. We've established that.

If your guitar player "loose the time" you need a better way to configure your live setup so that this cannot happen. To me that's the problem you should be trying to fix. Redefining the available functions and wishing cars fly, is not practical, at this point. Send the "time reference" to your guitar player through the monitor speakers, this way you don't wind up requesting things like arpeggios that start without instructions.

Route the Montage click to the assignable output, so in the measures with no drums, the click will keep them so they don't lose the time.

Thanks Bad Mister. Ok but we play also in a small place and I can't use click on monitor.
Take the things of "restart button" like a suggestion to implement in next firmware (I don't want to be heavy but my old fantom g had this feature, so I hope that should be possible in the montage too)
It's 2 days that I have montage and I'm very happy but it could be better in some things I think....expecially with the contemporary technologies.
Example: Now that I'm exploring the sounds to prepare new programs I'm very disappointed about the time that it take to switch from one program to the other. My last 4 keyboard: fantom g, nord stage2, Jupiter 80 and integra switch program without delay or latency, but I'm very sorry not montage.
Anyway montage is fantastic keyboard.
Best regards