Is there a way to reassign the MOD wheel on a synth within Sonar so that it controls something besides Modulation? E.g. expression, etc.
 
I'm sure it's simple but I can't find it :-)
 
Gavin

Depends on the synth, and on the keyboard. Each synth has its own way of handling incoming MIDI CC events, and some allow you to remap which events control which parameters. Native Instruments synths tend to let you right-click on the button or knob in the UI and set it to 'learn' which CC control to use when you next move one. Others may differ. The synth docs should tell you more. (But right-clicking wildly is always worth a shot.)
 
Some synths do accept incoming CC events and connect them to different parameters, but they may not let you reassign which events go to which parameters. In that case, you'd have to reconfigure your keyboard to have it send something other than CC1 for the mod wheel.

PilotGav
Is there a way to reassign the MOD wheel on a synth within Sonar so that it controls something besides Modulation? E.g. expression, etc.
 
I'm sure it's simple but I can't find it :-)

Mod Wheel sends CC1. Apart from already mentioned by Kylotan approaches, there are at least 2 other methods:
 
1. you can use MIDI FX (for example TenCrazy "CC Map") to modify CC1 to something else. That can be done "on the fly", so original MIDI track still has CC1 (also works for real time playing) or it can me applied to MIDI clip.2. you can use Control Surface plug-ins (GenericSurface, ACT MIDI or my own) to control near any parameter in  Sonar.