HIMA F7113 F7113 | HIMA | Power Module The I/O modules are used for signal transfer and signal matching between the plant and the central modules. The input and output circuits are always fed into the I/O modules via cable plugs on the front side. The status of the digital output signals is shown on the LEDs of the cable plugs. The power supply is either via the cable plugs or via the I/O bus board. The order of the different I/O module types does not matter.