Hi,
Look like noone else wish to reply.
i presume you have your pedal connected to your Keylab MK2 controllers expression jack input.
In generel midi mapping Volume by default is controlled by midi CC 7. The Expression pedal by default is mapped to midi CC 11. Expression is not the same as Volume.
You can change the midi CC for the Keylabs Expression pedal (at least in Midi Control Center (MCC) (i don't have a Arturia controller.), if you wish, and then it will control the main volume in many applications out of the box. But - especially if you only have one pedal - i will not recommend you to do it by default, as Expression pedal on midi cc 11 is used to control many other things in different applications - including perhaps controlling levels. And that will not work, if you change the Midi CC from midi CC 11 to another midi CC.
Expression pedal on midi cc 11 is often used as a modulator in modulation matrixes.
Volume can be controlled in different ways in different applications, and when using Expression pedal midi CC 11 to control the volume, then it has to be assigned to do so, in a way the application allow it to.
It's not allways a good idea, to use the main volume parameter to control the volume.
Often the main volume is set to the max possible output. Then the Expression pedal can control other parameters that control levels up to the level set by the main volume. It can in example be a VCA level parameter or other level/ volume parameters. This prevent the output will get to loud and distort, when you use the pedal.
But as with many things, then it can be a matter of preferences on how to use things. There are many ways to do things. Setting limits for a control can also be a possibility. It also depend on your equiptment.
Things can depend on the applications you use.
I recommend, you try to learn about midi CC, and to find out how the applications, that you wish to control work. A manual for your controller can not cover this.
