How to run Sequencer plugin?

After successfully receiving output events from plugins (see my post here), my own VST3 host can receive those NOTE ON/OFF events from a Chord-plugin and successfully plays them in a soft synth.
I tried the same with a sequencer plugin. But although it also now could produce output events, it does not produce anything. When loading that plugin in a DAW it immediately produces MIDI output. But it seems to need some input (a MIDI clock?). So do I need to send in MIDI CC messages? Is there a common standard, which messages I need to send to the IMidiMapping interface? That interface is present in my host and found when the plugin is loaded and initMidiCtrlerAssignment is executed. But what else is required?
Thank you!

You need to fill the relevant members in ProcessContext of the ProcessData struct.