An interlocking system for connecting a programmable logic controller and a power supply of an industrial control and automation system is provided. The interlocking system includes features configured to facilitate coupling with a panel or rail and a plurality of vertical slots and a latch disposed on a side surface of the power supply. The latch includes a first attachment feature disposed along a flexible tongue cantilevered proximate an opening in a housing of the power supply such that the tongue can flex into the opening. The interlocking system also includes a plurality of hooks and a second attachment feature formed on a side surface of the programmable logic controller. The plurality of hooks are configured to slide along and engage with the plurality of vertical slots such that the programmable logic controller and the power supply are held together horizontally and the second attachment feature is configured to couple with the first attachment feature to resist disengagement of the plurality of hooks and the plurality of vertical slots.