G4 I/O Family Opto 22 G4 I/O Family offers I/O modules with an LED status indicator on the top of the module and a more compact footprint than the previous G1 I/O modules. The G4 product lineup includes not only discrete and analog I/O modules but also controllers, battery packs, fuse clips, tools, and accessories. The discrete I/O modules can switch up to 3A per channel, and each module is individually fused. The analog I/O modules provide complete electrical channel-to-channel isolation, which eliminates troublesome ground loop problems. The Opto 22 G4 products are guaranteed for life and are suitable for new installations, legacy Optomux and mistic systems, Raspberry Pi, and more.