The proximity switches, which are inductive as limit switches, offer greater process reliability when operating a linear axis. Waterproof, dustproof and no mechanical or electronic wear. These are the advantages over using mechanical proximity switches. You can see here how to connect the inductive proximity switch to the D3 DC motor control.
Tip For those who want to know and read more about the operation of the D3 DC motor controller, see here for the complete manual.