The optoTTL b-12 system can be used for the optical transmission of 12 volt 16 channels digital signals or for overcoming greater distances or for eliminating problems with mass potentials. Manufactured by
Transfer Electromechanical Relay Failsafe Switch, DC to 40 GHz, up to 10W, 2M Lifecycles, 12V, Indicators,
level shifting - TTL to +/- 12V conversion - what's a better way? - Electrical Engineering Stack Exchange