I am using the PX-5S to emulate a pedal steel guitar when connected to my iPad MIDI app. One of the functions that this app provides is the triggering of vibrato by the delayed pressing of a key. It works perfectly, except that if I press the vibrato trigger key immediately after the playing of a chord or note, the vibrato takes almost a full second to engage. If I press the vibrato trigger key one second, or more, after the pressing of a chord or note, the vibrato engages immediately.
It seems that there is no way to engage the PX-5S vibrato via MIDI until after a chord or note as been sounding for approximately one second. I have tried practically every possible combination of the MIDI vibrato rate, depth, and delay messages, but to no avail. In fact, I could not get the MIDI vibrato depth message to have any effect on the vibrato triggering time whatsoever. It seems as if that message is set to a nominal value, and any attempt to modify that value via MIDI is ignored by the keyboard.
P.S. My app’s vibrato triggering works perfectly on a Casio CTK-6200, as well as on some other keyboards, which shall remain nameless.