Midi through on S 750 ?

[zvirek]

Hi,
Is there any possibility to send MIDI signal from PC through PSR 750 ( connected via USB ) to External Harmonizer ( connected via MIDI 5 pin cable - MIDI out on PSR 750 ).

Details:
When I play MIDI song directly from PSR 750 , there´s no problem to send MIDI data to external Harmonizer  ( TC helicon Harmony M ).
BUT I prefer to play MIDI song on PC ( using PSRuti ), sounding from PSR 750, but then it doesn´t send MIDI date next into the Harmonizer.

I didn´t find any way in MIDI settings on PSR 750 how to make it ?

Can you help pls ?