The M5 memory slot of the Velleman PS3005D / Korad KA3005P is described in the manual. There is not much to it: To recall M5 settings, press M4 and turn the dial clockwise; To save M5, do nothing. It is auto-saved
A summary of serial commands for the Velleman PS3005D lab power supply:
I’ve just discovered an undocumented command of the Velleman PS3005D programmable lab power supply. This PSU is available as a number of clones like Korad KA3005P reviewed at EEVBlog. I don’t know much about the serial communication protocol in the other PSU variants, perhaps they are different.