Thank you for your reply.

I am looking for a possibility to change my sounds on my two Yamaha keyboards with my tablet.
I am using the app mobilesheets pro for android. If i select the text of my songs I can change with MSB, LSB and Pr Change the sounds on my Motif XS7. My Samsung tablet 10.1 is connected on the USB to host.
The problem is that i have also the Montage 7 but how can I connect it so that I can change the sounds on both keyboards. I only have one USB connection on my tablet?

I have solved the problem. I have used a USB Hub and it works.