The COM0 and COM1 terminals are not connected internally.
To improve the life time of the contacts, and to protect from potential inductive load damage, it is recommended to connect a free wheeling diode in parallel to each inductive DC load or an RC snubber in parallel of each inductive AC load.
Sink wiring (positive logic)
Source wiring (negative logic)
Source wiring (positive logic)
Sink wiring (negative logic)