The new S4000TH Hydrogen Sulfide Gas Detector from General Monitors is designed to protect people, equipment, and plants from the dangers of hydrogen sulfide (H2S), and features the HART communication protocol for ease of field communications. HART is a field-proven instrumentation communications protocol that provides two-way digital communication without disturbing the integrity of the 4-20 mA analog output. HART permits several variables, parameters, device configuration, and device diagnostics to be transmitted digitally at the same time as the analog signal. Unlike other digital communication methods, HART is backward compatible with the installed base of instrumentation in use today.