After the gig we did some tests, and it was still the same situation. All controll knobs on the M-Audio did things they weren't suppose to do: the volume button turned into some effect trigger, the modwheel changed the volume, the tremolo wheel changed something else,... The +1oct button even CHANGED the sound preset on my main keyboard!

...and you conclude the problem is the MODX?

Putting the MIDI keyboard off and on again did the trick, for a while.

If resetting the MIDI controller fixed it, even for a few seconds, I think you might conclude the controller is the issue. I can tell you that no normal function could turn the +1Octave command into a Program Change message... on its own.

Does anybody have an explanation for this? We don't really know where to look at this point, and a gig is coming up...

Although this might be viewed as self serving, I’d look into getting any other MIDI Controller. At least borrow one to do some tests.

How do you have your MODX Set for MIDI I/O Mode?
Go to [UTILITY] > “Settings” > “Advanced” > “MIDI I/O Mode”

If the M-Audio MIDI keyboard's MIDI OUT port (5-pin DIN standard MIDI cable) is connected to MODX's MIDI IN port -- and this is your only connection -- then it doesn't matter what MODX sends (complex or not). The M-Audio will not have its MIDI IN port connected so it will not RECEIVE any MIDI. It will only send (one way) to MODX.

This wouldn't make an instrument "go wacky" - but sometimes if your MIDI clock is not set correctly - it can work for a time and then go unresponsive. Clock as internal will prevent this. Or ensure if clock=MIDI (external clock) that your connected device is sending a clock. Again, I don't think this is your issue in this case given the description. Just one of those considerations when connecting MIDI devices together.

Unlikely MIDI clock would change programs or send messages via the Octave button... highly unlikely.

That's why I said it's not his issue -- but it's one of those things that applies in this situation as a general thing. He's got more than one thing going on. The octave thing seemed to be under the heading of "this is what my M-Audio buttons are doing"

... pivoting to something else:

All controll knobs on the M-Audio did things they weren't suppose to do: [...] The +1oct button even CHANGED the sound preset on my main keyboard!

So I assume this is the +1oct button on his M-Audio that is doing this - not the MODX's octave button.

M-Audio going wacky creating problems with MODX, in response.

Could it have to do something with the fact that the M-Audio MIDI keyboard is powered by USB (from device directly to power supply via USB B cable in a cellphonecharger), and we're using no 9V adapter? Although my Yamaha main keyboard is set to receive MIDI through MIDI cable, maybe the M-Audio is confused wether to send its MIDI to the MIDI cable AND to the USB power supply cable?

You’ll need to contact M-Audio for what to do to power their unit properly.

Still doesn’t explain the messages it is generating... you should get a MIDI Monitor and get an idea of the messages it is sending.

A flash drive is bus powered (you don't hook a power adapter to one) - but the current draw is small enough we don't consider a flash drive is any load. This drive is the target device to plug into MODX's USB port. I would generally not advise using the USB port as a power source for external devices. It'd be better to just buy a cell-phone charger with enough current rating to power your USB keyboard and use that. Or a USB hub that's purpose is only to supply power - and DO NOT plug in the hub to your keyboard - but do plug the hub into a power supply. This, to me, isn't so much to steer the data - but that you may have overload issues on a USB port that is not really designed to supply significant power to downstream devices. It should be USB compliant - and so should your keyboard - but I would still advise against this sort of thing. If the keyboard has the option to buy a power adapter that skips the USB connection altogether - this may be a "cleaner" option. And one that allows for more options should you want to use USB for data down the line but also simultaneously want a clean power supply not encumbered by the USB port implementation for power delivery.

At any rate - I'm not sure your M-Audio is going wacky due to power brownouts - although it's something quick to test with the cellphone charger test.

The MIDI monitor is always my go-to for this sort of thing. M-Audio is plugged into the 5-pin DIN, then take a look at MIDI messages coming in from MODX Port-3 on your DAW or in a stand-alone MIDI monitor. iOS has MIDI Scope (and others), PC/Win has MIDI-OX, mac has Snoize's stuff. On the DAW side there are several free plugins that provide MIDI monitoring support.

Don't filter out Sysex - but you can filter out the real-time messages. This is why I prefer MIDI Scope for iOS over something like MIDI Wrench. MIDI Wrench can't filter these out - so you'll see constant MIDI clock messages "washing away" what you're really looking for.

Don't filter out Sysex - but you can filter out the real-time messages. This is why I prefer MIDI Scope for iOS over something like MIDI Wrench. MIDI Wrench can't filter these out - so you'll see constant MIDI clock messages "washing away" what you're really looking for.

Just FYI, you can always defeat MIDI Clock at the source. In the MODX go to [UTILITY] > “Settings” > “MIDI I/O” > set “Clock Out” = Off

That covers MODX - but in the general case the source could be anywhere (MODX as a slave to another device's clock) and the tool is ultimately the easiest place to filter this out (one-stop shop). Turning clock off at the source could bite you where filtering it at the monitor will not. Presumably clock is being supplied because the slave needs it (is not set to an internal clock). My preference is to leave my configuration alone while debugging and use "better" tools.

... aside from clock, active sensing is part of the real-time messages as well.

That covers MODX

? What? This is the MODX forum. Turn “Clock Out” Off. Simple enough, not really a matter of your preference here (you can do whatever you like); it’s knowing that you can turn “Clock Out” Off. When not using it, you can shut it off.

Don’t let it prejudice you against a particular Midi Monitor program simply because you didn’t know how to stop Clock messages from ‘washing away what you’re really looking for...’
“Active Sensing” can be filtered. Simple enough, too.
That covers the MODX.

My point is that if MODX is receiving a clock from an external device - you cannot turn off clock at MODX. That's not a bias - it's a possible configuration. Having a tool that has less filtering capabilities than another is absolutely a valid reason to select one tool over another. Why would I suggest a less flexible tool? Even if MODX can be configured to turn off clocks it SENDS - which only covers half of the possibility landscape?

That active sensing can be filtered is an assumption which may not apply. Not all tools are created equal. Although, as for MIDI Wrench, active sense can be filtered.

As for preferences - I'm not sure I get it how a valid preference is not to "force" adjusting my MIDI setup because I choose one tool which is less flexible than another. Sounds like a reasonable preference to have. There's a 50/50 chance that MODX is SENDING clock. Lets just say that IS my configuration - MODX sending clock. There's two possibilities here - either something connected to MODX needs the clock to do its job - or it doesn't. I'm going to assume here that the clock is required and not ON "just because". In this case, why would I use tools that force me to change my configuration (turn clock send off on MODX) if I could use a "better" tool that doesn't? Something isn't jiving here and I'm not sure why there's any debate.

If, for the sake of debug, I've chosen MIDI wrench - which doesn't allow filtering MIDI clocks - then OK. I turn off MIDI clocks just for debug purposes. Maybe or maybe not this will still be a valid test. Lets say it is. Then I have to remember to turn the clock back on when I'm finished or something downstream is going to stop working. Still working under the assumption that MODX sending the clock is required for my configuration to fully do its job. That adds configuration steps into a workflow that would otherwise not be needed by choosing, and yes - efficiency is a preference here, the "better" tool with more filters. I prefer not to change configurations just for the sake of debug - because I have to remember to change them back. It's easier, more efficient, less to document, etc ... just to get the "right" tool for the job. Seems like a reasonable set of pitfalls to avoid if at all possible.

... for those who are curious, MIDI wrench can filter:

1. MIDI Active Sense (just one of the realtime messages)
2. SysEx
3. CC

MIDI Scope can filter:

"Voice Messages"
1. Note ON/OFF
2. Aftertouch (poly)
3. CC
4. PC
5. Channel Pressure (MODX type of aftertouch)
6. Pitch Bend
"System Common"
7. Time Code
8. Song Position Pointer
9. Song Select
10. Tune Request
"Real Time"
11. Clock
12. Start/Stop/Continue
13. Active Sensing
14. Reset
"Other"
15. SysEx
16. Invalid / Malformed messages

Many items do not necessarily apply - but it's helpful to have Active Sensing and clock filters. Aftertouch filters are useful too. Although possibly easy to handle by not mashing so hard - still good to have the option to squelch those without making any changes to either your playing or keyboard configuration if they'd otherwise get in the way of a debug session. Maybe you're just looking for a SysEx message - nice to be able to filter out note on/off (and everything else) so just SysEx are documented.

Tool allows for different filters on each channel (1-16) or a common filter for all channels.