So this is the scenario: my software (it could also be a control surfarce) sends MIDI to Cubase. In Cubase I want to listen to this MIDI to control an instrument channel with Guitar Rig as an insert.

The goal is to automate the parameteres of effects in Guitar Rig from the software, by sending MIDI CC messages. Here's how to do it:

Versions: Cubase Artist 9, Guitar Rig 5.2, OSX 10.11.

Part 1: the software

Here I just need to send some CC messages (I'm using an unassigned number, CC20) through the appropriate MIDI channel (in my case, channel 1), to a virtual MIDI port. I wouldn't need to do this if using a control surface.

Part 2: Cubase

Here I need:

• A VST instrument in the rack
• An instrument channel from this VSTi, with Guitar Rig as an insert.
• Two MIDI tracks:
  • The first one, listening to the port and channel set in Part 1. The output is to the VST instrument. This one will play the notes.
  • The second one, also listening to the same port and channel. But here the output is to the Guitar Rig insert MIDI in, otherwise Guitar Rig cannot receive the CC20 messages I'll be sending.

NOTE: right now, both MIDI tracks will be receiving all the midi messages from the software. This might not be efficient, or could even be problematic. It would be easy to send the CC20 messages to a different port, or filter them within Cubase with a MIDI Transform insert, if necessary.

Part 3: Guitar Rig

• On the left panel, choose Options, then click the Controller tab.
• Drag the white bar with the four-arrow-icon towards the knob or button you want to automate. This will link the control we're creating to that knob. Note that it's possible to link this control to multiple knobs/buttons.
• Click the learn button, and start the software, but to send CC20 only. This will connect CC20 with the knobs we've linked to this control. Done!