I have been frustrated using my expression pedal to control volume. If you only use yours in the studio, ignore this post. If you, like me, play in a live band (2 in my case), then this may really help you.
The typical calibration of an expression pedal gives you 0-100% over a very limited foot pedal range, 0% of course also giving you the tuner. Personally this is not very useful, as tuning at the start of a gig usually is good all night, or I can easily re-tune between sets if needed. What you sacrifice with this 0-100% range, which is hardly linear anyway, is the ability to really craft your volume to the crowd. Where I play this grows as the night grows, as does the volume and intensity of the band. Rather than running back to the amp to jack up the master volume (we have no dedicated sound person), the reference manual gave me a much better solution.
Page 30 describes the "volume pedal range," a feature I had overlooked, but won't again. Here's how to use it: Hit the "Rig" button, go to page 3. Adjust the volume pedal range downwards. I am experimenting currently at -1.3 which gives me at the EP heel position about 60-70% of max volume, toe position being 100%. So I start the evening at the heel position, ramp up to toe position as things get rocking, and this actually emulates rather well a true volume pedal versus the limited range of an expression pedal. I then "lock" this setting so it works on all rigs globally, with the exception of wah and pitch pedal rigs.
No, you can't do volume swells with this, but I wouldn't anyhow. I use my fingers and the volume knob for this. This also doesn't apply to rigs with active wah or pitch pedals active, naturally. But those I only use sparingly, so it's not any great loss there. Try it, you may find this helpful, as I did and still do!
And here I thought it was your idea... how do you say that title in German?