When you are playing a Performance on the MX, the 16 buttons also act as MIDI channel select. So for example, if you hit button 9, you will be transmitting on channel 9, and the MODX will play whatever sound you have placed into Part 9. (Note that the MODX itself must be in Multi mode for this to work, but it probably already is.)

Hi AnotherScott and thank you for this information. Very helpful.

Two more small questions 🙂
Does the MX support split and layer so that I can play two sounds from the MODX as for example a split?

And I think that the settings can be stored in a performance? If so, I can save both performances on the MX and MODX with the same song name. Or even I can call a performance using midi

Does the MX support split and layer so that I can play two sounds from the MODX as for example a split?

As provided by Yamaha, this function is only available for channels (parts) 1 and 2.

The MX lets you play parts 1 and 2 simultaneously (with its split/layer function). Whenever you do that, you are also transmitting on channels 1 and 2, and so can split/layer MODX Parts 1 and 2. If you want more flexibility than that, you'll have to employ some additional software. There are two computer-based editors for MX... Vycro MX and the tools from John Melas. The former appears to be discontinued, but you may still be able to locate it somewhere. My understanding is that either of them should let you create MX Performances that will transmit on the combination of channels of your choice, which would in turn allow you to trigger the combination of MODX Parts of your choice.

Alternatively, you could send the MIDI from your MODX to an external device and have that device "re-channelize" the incoming MIDI as desired. For example, you can connect your MX and MODX to an iPad running Camelot Pro or Keystage or other similar app, and the app will route your MX MIDI to whatever MODX channels/parts you want to send it to. If you use a laptop, there are also Windows and Mac apps that do this (Camelot Pro as well as others). You can also use a hardware device like the Event Processor from MIDI Solutions, though that will be less flexible.

And I think that the settings can be stored in a performance?

The MX itself does not store MIDI settings in a Performance... it simply works the way I described, no matter which Performance you call up (e.g. button 9 always transmits on channel 9). However, using the Vycro or John Melas software, you could save Performances with different combinations of simultaneous Parts, which therefore also means different combinations of MIDI channel transmission, I believe.

Or even I can call a performance using midi

The MX cannot send user-definable Program Changes to the MODX to call up a desired MODX Performance. However a MODX can send user-definable Program Changes to the MX.