An enhanced version of Banner’s XS26 safety controller with built-in in-series diagnostics (ISD) is designed to simplify installation, provide comprehensive real-time data about automation safety equipment and prevent or reduce downtime. The XS26-ISDd is expandable, allowing users to configure and monitor up to 394 connected safety devices, such as e-stop buttons, safety switches, safety light screens, two-hand controls and rope-pull switches, and it controls up to 68 independent safety outputs. Up to 32 in-series diagnostic devices can be connected in an ISD chain with M12 connectors and four-pin standard cabling provide fast, error-proof connection at Category 4, PL e, and SIL CL 3 ratings. Two pins are used for power and two pins for the OSSDs. The ISD rides on the same OSSD pins for a simplification of wires. Outputs on each device are continuously monitored to detect any faults, including short circuits, which is designed to eliminate the possibility of fault masking at any point in the system.