Using a master keyboard controller, there a few Motif parameters that I’d like to be able to focus:  the Portamento and the ARP.

I’d like to be able to assign a button to simply turn the ARP On/Off.  Also, I’d like to assign a knob/slider to adjust the ARP’s tempo speed and Octaves, as well as a dedicated button used for TEMPO TAP.  Finally, to assign a knob/Slider to scroll through all the ARP’s Patterns.

As far as Portamento control, I’d like to assign a button to turn Portamento On/Off as well as a knob/slider to control the Portamento’s glide Speed.

The main reason I’m posting this question is to confirm if the Motif XS Rack is indeed capable of responding to the control information I’m requesting.

Other note: I’ve been eye-balling Auturia’s new KEYLAB 61...anyone having any good reviews on this controller?

thanks,

Welcome to the Forums!

I’d like to be able to assign a button to simply turn the ARP On/Off.

You can turn the Arp On/Off by sending a control change message (default is cc090); You also can turn Arp Hold On/Off by sending a different control change number (default is cc089). As you begin working with Motif-Rack XS Arpeggiators you will appreciate thus difference. Both are assignable parameters.

Also, I’d like to assign a knob/slider to adjust the ARP’s tempo speed

That’s on your controller’s ability to generate and transmit clock. Tempo is not an assignable function, like to a CONTROL CHANGE, Tempo is its own category of message within MIDI. Set the Rack XS to follow external clock and adjust that clock at your controller. This will affect not only the tempo of the arpeggiators, but adjust the Rack XS’s Tempo Delays, and the tempo sync’d LFOs. Yes, the Rack XS slaves to external clock.

...and Octaves, as well as a dedicated button used for TEMPO TAP. 

Again pretty standard, MIDI controller functions… and depends entirely on the capability of your controller… You send tempo, any MIDI device set to receive clock would follow that command. Make sure your controller can set the Tempo it sends by tapping something… The Rack XS is just a follower at this point… It will not care how you generate the tempo command, it will simply follow that tempo. Make sense?

Finally, to assign a knob/Slider to scroll through all the ARP’s Patterns.

Yes, the Rack XS can select Arps dynamically from a knob, slider or button… You can either select a specific Arp 1-5 by sending a specific value for a control change number (default is cc085) value of 1-25 selects Arp1, 26-50, selects Arp2, and so on; or you can advance through them one after the other.

As far as Portamento control, I’d like to assign a button to turn Portamento On/Off as well as a knob/slider to control the Portamento’s glide Speed.

Again you looking at the wrong end of telescope here. You turn Portamento On/Off usually with a Foot Switch, in MIDI cc065 has been fixed as this function. It’s like asking if cc064 will work the Sustain function, not to worry, the Rack XS will turn Portamento On/Off in response to cc065, and if the Amplitude Envelope Generator is set properly to allow for it, cc064 will act to Sustain.

Also standard in MIDI Control Change message 5 is used to set Portamento Speed… Yes the Rack XS will respond to this cc005 Portamento Time parameter, much the same as to any fixed Control Change function… cc001 Mod Wheel, cc002 Breath Control, cc004 Foot Control, etc., etc., etc.

The main reason I’m posting this question is to confirm if the Motif XS Rack is indeed capable of responding to the control information I’m requesting.

And, indeed it is!

You can download the Manuals, Data List booklet, and the Motif-Rack XS Editor Standalone/VST. You will want to get familiar with the Editor, because it gives access to the full compliment of Voice edit parameters.