For using a HD500 as midi controller feel free to use my patch as a starter.
first make sure that your HD500 are set to FS mode ABCD this are don by press and hold the view button and goto page 1 set it to use FS mode: ABCD.
on the Kemper make sure to go to Rig and set volume to pre and lock it there, also make sure to have a wah in stomp A and under wah set pedal mode to on.
wah on stomp A are to be saved to rig as off (get switch on by tue switch when switching to exp 2 on the HD500)
The HD 500 are set to work with exp 1 as volume and wah as exp 2
tuner on Tap/tuner button
bank up/down as bank up/down
program number 1->4 are send from button ABCD on bank 1 and program number 5->8 are send from button ABCD on bank 2 and so on.
setting a rig on the Kemper to midi 2 will make i switch on bank 1 button B, setting a rig on the Kemper to midi 7 will make i switch on bank 2 button D
FS1 to FS4 are set to switch on/off stomp B,C,X, and Mod and for the button light to work I have put in a stomp on the HD500 to be on/off.
just remember save the HD500 stomp on/off state the same as the Kemper stomps on/off state for the button light to be right .
so just copy my patch to all positions on all banks you are planing on using and it will work
hope this can be of any help, feel free to ask and I will try to assist as far as I can
[url]https://www.dropbox.com/s/k7wx22knl8e7rn8/HD500 midi patch.h5e?dl=0[/url]