Cakewalk Sonar is a music production software from Twelve Tone Systems (www.cakewalk.com).
Natural plugin system for Cakewalk is Direct X plugins, so there are several steps needed to adapt WIDI VST for Sonar 4:
Launch "Cakewalk VST Adapter 4" , it is a separate program provided along with Cakewalk Sonar. Locate the folder where WIDI VST is installed.
Select "widi_vst" item from the list of plugins and open its property page with the "Properties" button. On that page check "Enable as DX plug-in" and "Configure as DXi synth" check boxes. Also, make sure that window size is set up correctly. Set the window width to 400 pixels and the window height to 320 pixels. Press "Ok" and follow further instructions.
This is required to do only once.
Using WIDI VST Plugin in Sonar 4:
1. Open a project with at least one non-empty Audio Track in Sonar.
2. Make sure that "FX" button in project window is turned on (green) and press the right mouse button on the plugin list (see the image below). In the context menu choose "DXi Synth"->"VST widi_vst" item. WIDI VST window should appear with the plugin name added to the list.
3. On the Option page of WIDI VST choose the method you want to use for MIDI output. "VST HOST" has no effect - Sonar cannot get MIDI data from VST plugins. You can select "MIDI FILE" or "MIDI OUT". If you chose "MIDI OUT" then you should select a device different from the one used by Cakewalk. The list of devices is located under the "MIDI OUT" button. See routing MIDI for details.
Now the plugin is activated and upon playback start the plugin will output recognized notes to the MIDI Out Device or to the file.