Sending MIDI from a VST to another module?

Alright, MIDI interlinks have been introduced in version 0.99-beta.

You can now use pure MIDI VST plugins (sequencers, arpegiators, effects etc)

I am trying to get this MIDI interlinks to work using "UplandToys BallSequencer 1.5":

http://upland.no/download/

I have it's MIDI output connected to the input of a VSTi synth "OatMeal". I have Rack Performer 'play' to generate some timing info. But the 'balls' on the interface do not work. I am not able to power "on" BallSequencer. The other devices have their lights on.

If I "swap" Ballseqencer with Oatmeal, then Ballsequencer turns 'on' and the balls work. But now Oatmeal is turned 'off'. So I connect the audio out of Oatmeal to the master module and now I can hear the Ballsequencer performance as played through Oatmeal.

If I deactivate the audio paths from Ballsequencer to the master module then Ballsequencer stops working. If I re-connect the audio paths then Ballsequencer works again.

I guess there needs to be a way to turn on pure MIDI modules.

I think it would be helpful if the RP wrapper had a MIDI activity LED to show if there is an actual MIDI connection. In fact this would be nice with all wrappers, an activity LED or small meter showing Audio and/or MIDI i/o.

RP will consider a VST to be a pure MIDI plugin only if it can send MIDI and it declares no audio I/O. In which case the plugin will automatically be powered when the patch is powered on.

But most of the time, and I believe for compatibility reasons with non-modular hosts, most MIDI plugins do declare some audio I/O. For some these I/O are dummy but for others they might be useful (for instance audio+MIDI plugins)

The trick is to have the MIDI/sequencing plugins run *before* the sequenced modules. In your example (I didn't test your linked plugin yet) I imagine you would need to connect both modules outputs to the master module down below, then in the patch menu, select the "execution order" item. From there, you would be able to increase (+1) the weight of the Ballsequencer, such that it is always executed before Oatmeal.

If for some reason a MIDI plugin does output something on its audio out pins but you just need its MIDI capabilities, then you could always connect the outputs to a dummy CamoGain module and set the gain volume down to zero.

I hope this does clarify things a bit?

PS: please note that RP controller class modules always run before the instruments/generators so you don't have to set their execution order in most cases like with VST MIDI plugins. You need to set their execution order when you have a controller automating another controller etc. otherwise it will work but there will be a slight control latency.