I am trying to select performances ....

Check to see if the external controller can send MSB LSB and PC information.

MSB denotes sending CC #0 with some data value representing the MSB value.

LSB denotes sending CC #32 with some data value representing the LSB value.

PC (aka Program Change) is not a CC message, but a dedicated message. Hex 0xC# where #=0-F representing the channel number (0xC0-0xCF) with a data value representing the program number.

MODX has a table of MSB+LSB+PC in the data sheet which describes how to access User, Library, or Preset Performances. They each utilize different MSB/LSB combinations.

But none of that is really important to dig into unless your controller supports sending such messages.

... and other functions [on MODX] ...

More detail?

As far as the pads and switches on your external controller - I have no idea what you want to do. Many of MODX's own controllers and buttons can be virtually pressed/moved through MIDI messages - but you haven't described the detail of what you want to access on MODX's side. Here, the data list also provides the relevant documentation.

I am struggling to figure out the MIDI address information for user performances.

Call up the Performance.
Tap the Performance Name title box to view the pop-in menu.
Touch “Property”
Each Performance will report its location by displaying its Bank (by name) and its MSB/LSB (Bank Select) and Program Number 001-128.
When the MODX is in MIDI I/O Mode = Multi, you can send the Performance Select information (MSB/LSB/PC) on any MIDI Channel 1-8... that will address the entire MODX

The MODX’s KBD CTRL (Keyboard Control) Performances can occupy as many as eight Parts for simultaneous play from the MODX keys, each Part occupies a separate MIDI Channel 1-8, respectively.
__ The KBD CTRL icon (green when active) links as many as 8 Parts together for direct play from the MODX keys.
Yes, when the MODX is in MIDI I/O Mode = Multi, it is transmitting on multiple MIDI Channels, simultaneously.

The MODX is 16-Part multi-timbral. This means you can use it with a different instrument sound on each of its 16 Parts. (As we already explained, you can link any of the first 8 Parts together via KBD CTRL). Those Part Numbers not being addressed (linked) together via KBD CTRL can be triggered on the correspondingly numbered MIDI Channel... you can do so by *selecting* that Part directly.

For example, you might link Parts 1 and 2 using KBD CTRL, and use the Sequencer to play the other 14 Parts via the Sequencer.

You might link Parts 1, 2, and 3 using KBD CTRL, and use the Sequencer to play the other 13 Parts via the Sequencer, and so on.
You can link as many as 8 Parts, 1-8, for personal play, and use the Sequencer to play the other 8 Parts.
Obviously, you can work like any multitimbral synth and use just one instrument per Part, and just one channel per Part, 1-16, if you wish.

Other MIDI I/O Modes
The MODX has two other MIDI I/O Modes, (Single, and Hybrid) that allow a combination of internal and external control (if your external control device does not have 8 Zones, these modes will assist your external controller by allow it to address the KBD CTRL linked Parts on a single selectable MIDI Channel.

Finding what you need
When on the HOME screen, and [CATEGORY] is pressed, the “Performance Category Search” is launched. Here you can look through the hundreds of MODX Performance programs.
All listings in blue are Multi Part Performances occupying multiple Part slots.
All listings in green are Single Part Performances occupying a single Part slot.

All green listings can be recalled as Single instruments — additionally, each of these instrument programs can be recalled within the current Performance. This means - when using a Sequencer, for example, you might have a synth bass in Part 3, but at measure 49 of your sequence you might want to change to an electric bass, you can do so by using the appropriate (Single) MSB/LSB/PC for that program. Instead of changing the entire Performance you can generate an MSB/LSB/PC that when placed on the Track addressing MIDI Channel, will only change the synth bass to electric bass in Part 3, without affecting any of the other Parts.

So all Single Part programs have two sets of MSB/LSB/PC — one that recalls it as a standalone Performance, and a different one that allows it to be recalled individually on its own Channel within the current Multi Part program.

Thanks for both replies, I understand now after some experimenting I discovered/remembered that to get MODX PC 001 you actually have to send 000 etc so I now have the performance selection link sorted. Had to set the MODX to MIDI=single to get the controller to play all parts. If I wanted to toggle the ARP button on/off where would I find the CC and on/off values ? i started to scour the Data List , am I looking in the correct place ? The controller device is programmable for the following MIDI functions

Note
CC Toggle
CC Momentary
Program Change
Panic

If your external controller supports sending SysEx - you can set/clear Master or PART Arppegio switches using SysEx. SysEx isn't in your list, so I'm assuming that's a no-go.

No issue - there are other ways. Scene buttons can be selected through MIDI CC (CC Toggle would be appropriate). And scenes can store the Master ARP switch setting (on or off). Therefore, you could assign two scenes that only turn ARP on or off but turns memory OFF for all other scene functions. This would be an indirect way of MIDI CC addressing the Master ARP switch.

This isn't what you asked for - but also keep in mind that the footswitch can be set to toggle the master ARP switch also. I know this isn't MIDI or addressable from an external controller - but something possibly in the general wheelhouse if that alternative works for you.

And yes - PC vs Program Number - Yamaha docs starts numbering at "1" and MIDI starts numbering at 0 - so there's an offset of 1 to apply.

Thanks Jason , thats opened a can of worms . My controller doesn't have sys ex but i think On Song on my tablet does (but lets hold that thought). This then poses 2 questions given that the controller offers up the following when you elect CC Toggle
1. Channel [value]
2. CC [value]
3. On [value]
4. Off [value]

Where do we find the 3 values for each scene switch? and I guess if i find those I will also find the sys ex