G1 discrete and analog I/O
Although typically not recommended for new development, reliable G1 I/O modules are still used in Optomux
, and direct I/O systems.
The red-black-yellow-white color-coding scheme Opto 22 designed for G1 digital was later used for G4 and SNAP I/O, and it remains the standard today.
First developed in 1978, G1 is the first generation of digital I/O modules with plug-in racks for microprocessor-based control. G1 (also called "Standard I/O") quickly became the world standard form factor for I/O and created the component market for computer-based I/O.
Five years later we added G1 analog: the first optically isolated analog I/O modules with intelligent racks, marking the beginning of a new era in computer-based automation.