I prefer to use Expression (instead of Volume) for fade outs and fade ins, especially in the midst of a sequence.
I would also like, as I can with Volume, to use a knob INSTEAD of a foot pedal. It's so much more accurate that way. It's been a while and I may not be describing it quite right, but I went into the Assignable Menu and tried a few things, but when I went into Overdub the knob turn didn't create the EXP events.
Since I'm still not sure why it didn't work, perhaps someone could explain it to me. OR tell me how it CAN be done.
I guess that's a NO....... (sigh)
I don't own a MOXF, but even so, your OP seems a little short on detail, requiring a certain amount of interpretation and assumption to be made by the reader.
"Expression" to me, means an "Expression Pedal"... i.e. a Foot Pedal, similar to the Yamaha FC7.
I can tell you in the MODX world, any "assign controllable" parameter can be assigned to either a Knob or a FootPedal (Expression Pedal? Foot Controller? ) . Also, In the MODX world, a FC can be used to control the Knob which is assigned the parameter in question, by way of the SuperKnob... but that's another story, not available on the MOXF.
So what exactly is it you want to achieve?
I asked the question because in the past I tried to use one of the Assignable Knobs as Expression (CC 11) and even though setting held as Expression, when I used the knob some other event (one of those radically abbreviated CC effects that I had no idea about). After a query on the Motifator Forum that didn't answer anything except suggested there was possibly something wrong with my knobs or whatnot.
So I just two days ago returned to try it one more time and it worked exactly as you'd expect.
So YES you can assign Expression to an Assignable Knob. It works great and I WAY prefer it to an Expression pedal that seems like a sledgehammer vs a ball peen.
As for WHY the events got printed as this "other" command, I'm not sure. But I THINK it could have something to do with the fact that I left the Expression PEDAL plugged intro the Foot Controller jack -- AND/OR: I recently opened up all three of my FC7 pedals, ready to replace the pot in each cause they were making terrible crackling noises and printing "bad" numbers. I never had to replace the pots because the first thing I did was spray some electronics cleaner on the pertinent parts and all three FC7 pedals were fine again.