The default CONTROL NUMBERs of ASSIGNABLE CONTROLLER are as follows:
FOOT CONTROLLER 1 _ cc011
FOOT CONTROLLER 2 _ cc004

cc011 Expression always adjusts volume of the tone generators assigned to the channel.
cc004 Foot Control is assignable within the program it is used. It. An be assigned to control certain parameters within the assigned Insertion Effect.

You are given one (fixed) as volume, the other is assignable within the Performance. This works for most, however, you can globally change these defaults, if you wish.

The CP4 Stage is programmable - this is good and bad news, bad if you think all you need to do is plug in the pedal and it does something... Good news if you want to roll up your sleeves and think about what you'd like to control within your Performance.

For example, you might want to switch speeds of the Rotary Speaker INSERT EFFECT. If the default speed is set to "slow" you could set the FC2 CONTROLLER to "EffA(+)" this would allow the pedal to increase the speed as you set toe down, and go slow at heel down.
If the default sipped is set to "fast" you could set the FC2 to "EffA(-)" - this would allow the pedal to be slow at toe down and fast at heel down.

In the Data List Booklet you can find which Insertion Effect parameters are available within each Effect Type, if any, to assign to your Controllers. Only selected parameters are available for assignment. But you do have to make the assignment.

If you get stuck you can always post your question here.

Thanks for the reply. Sounds like with a little bit of research in the data list I'll be there.

It's pretty simple once you get going. The parameter that is most often found useful is the one typically that is marked as the available parameter. This is not about editing, this is about assigning control over the most often used parameter within each effect type. It is pre-selected. For example, on a Rotary Speaker, it is the SPEED CONTROL switch - this is what you had as real time control on a B3 with a Leslie. (Transition Time was not real time adjustable! 😉 If you are thinking controlling deeply each parameter, that is not what happens here. The parameter that makes the most sense is activated when you make the assignment. Not all Effect Types have an available parameter. So you need to make your assignment based on the Effect TYPE that you choose.

The (+) and (-) are directions so that you can use the one that works for you in your situation. If for example you like the Rotary Speaker to initially be SLOW, versus FAST. You can select the one that works for you and your pedal situation. One direction will work for you... the other is for settings that begin in opposite position. In general, they are provided for when you need the pedal to go positive from Heel Down to Toe Down versus negative when moving from Heel Down toward Toe Down.

I believe what Bruno does is assign Part volumes for two of the Parts to the two expression pedals.

For each Performance where you want to do this, go to each Part where you want to control the volume, and go to Controller -> FC1 (or FC2) and select Volume.

When you do this, FC1 (or FC2) will control the volume of that Part (whether it be Main, Layer, or Split ... and of course you can do this for only two of the three, since there are only two FC jacks.)

Sorry I can't give detailed button pushes like BadMister does, but my CP4 is elsewhere. I'm sure he can explain this better than I did. Also, there may be another step (disabling FC1 as Expression applied to all three parts).

See CP4/CP40 Stage Reference Manual page 21.

I love my cp40 but I have trouble setting up the expression pedal to only control the volume on the layered voice. I have all the instructions and have gone through them many times and I can only set it so the expression pedal controls both the main and the layer as I wanted to only control the layer voice help please