I am trying to find out if I can make tempo changes with a MIDI controller. I know they can do that in Cubase.

No, SONAR does not allow remote control of tempo except by MIDI/SMPTE/MTC sync as a slave to an external clock source, which I don't think is what you mean. 

brundlefly
No, SONAR does not allow remote control of tempo except by MIDI/SMPTE/MTC sync as a slave to an external clock source, which I don't think is what you mean. 

There's been a couple of feature requests to do this. OP is encouraged to add his/her voice.

hi,
 
maybe this does the trick:
https://www.youtube.com/watch?v=kJI7eA4zdYQ
i'm pretty sure sonar x* pro has no such an audio effect on board..
Free VST - STRETCHA Time-Stretching - vstplanet.com

Astra-Ios
hi,
 
maybe this does the trick:
https://www.youtube.com/watch?v=kJI7eA4zdYQ
i'm pretty sure sonar x* pro has no such an audio effect on board..Free VST - STRETCHA Time-Stretching - vstplanet.com

Stretching a single audio track is not the same as controlling/changing tempo in a project. Also, this is 32 bit only. This is more akin to Varispeed. Craig Anderton posted a methodology to achieve a Varispeed effect within Sonar a while ago (should be searchable for anyone interested).

That's a pitty we don't have this in Sonar. I hope they will add this in near future. 

wienryk
I am trying to find out if I can make tempo changes with a MIDI controller. I know they can do that in Cubase.

That capability was removed from cubase 7 and up.