ST4-C11 is a compact Type 4 safety beam sensor controller designed for machine guarding and industrial safety applications. It features selectable PNP or NPN output polarity via a single output polarity selection switch, reducing the number of parts required for system integration. The controller supports series connection of up to 6 sensor head units with automatic interference prevention, and can be cascaded with up to 3 controllers for interference prevention across 18 total sensor heads. Operating at 24 V DC with current consumption of 100 mA or less, it provides dual control outputs (OSSD1, OSSD2) with a maximum current of 200 mA per output and response times of 25 ms for OFF response and 90 ms for ON response (auto reset). The device complies with critical safety standards including IEC 61496-1/2 (Type 4), ISO 13849-1 (Category 4, PLe), and SIL3 certifications, making it suitable for protecting large facilities where installation of physical guardian fences is difficult.