GE’s multi-purpose Vital Logic Controller (VHLC) provides control of power switch machines and DC lighting of signal lamps, replacing most vital and non-vital relays at an interlocking. Its track-proven technology and years of reliability have made the VHLC the leader in solid- state interlocking control in the North American rail industry. The basic system consists of the chassis, power supply, vital logic processor, auxiliary communication processor and a site-specific module.