How to send MIDI message to external device?


Im using Cubase SE3. My setup works grate, when recording and playing MIDI. I have several synths in my setup assign to different channels. My question is really simple: How can I transmit a MIDI message to a particular synth enabling it to start the arpigator and when to stop it?
The synth I want to control is an Korg Triton Extreme. I use a particular program in “combi mode” that has an arp/rythm section as part of the total sound setup. Manually I can start the arp/rythm section by pressing and repressing a start/stop button. But I want my Cubase to this for me, so I dont have to do this manually.
One thing that works is that when my cubase song start and my synth start/stop buttom is “armed”, red light, it starts the arp/rythm as soon as the first midi notes are played. This is ok sometimes but in other songs, I want to control when it shall start. At the end of the song, the synth will continue to play the arp/rythm part until I press the start/stop button. Again, I want to avoid this, and let Cubase due this…
Thanks in advance!

So your synth is using midi clock that you’re sending it from cubase?

Does SE3 have automation?

You could setup automation to just turn the volume down on the track until you need it.