Sensor ( 4 pins )

Red  +24V
Blue   0V
Yellow } contact 
Green  } closure in ( short these two wires together for logic 1 )

N.B. yellow and green wires of unused inputs must be connected together


Output ( 3 pins ) to USB-controlled ac mains relay

Red    NC ( normally closed - with respect to COM with no power applied, single pole double throw relay out )
Blue   NO ( normally open - with respect to COM with no power applied, single pole double throw relay out )
Green COM