PISO-P8SSR8AC/P8SSR8DC cards provide 8 optically isolated DI channels and 8 solid-state relay output channels. The DI channels provide 3750 Vrms isolation protection, allowing the input signals to be completely floated so as to prevent ground loops, and isolate the host computer from damaging voltages.

Relays are used where it is necessary to control a circuit using a low-power signal (with complete electrical isolation between the control and controlled circuits), or where several circuits must be controlled by one signal. Solid-state relays (SSR) control power circuits using a semiconductor device instead of moving parts to perform switching. The advantages of SSR include long-term reliability, no contact bounce, no sparking, silent operation, decreased electrical noise when switching, and faster switching than electromechanical relays.