Siemens XTRI-S Single Input ModuleThe Siemens XTRI S is an intelligent single input interface module for monitoring a normally open or normally closed dry contact on the SLC. It includes ISOtechnology dual isolation for NFPA 72 Class X (Style 7) survivability, a tri color status LED, and configurable wiring: isolator mode or polarity insensitive wiring in non isolator mode using SureWire. The device occupies one loop address. Also known as P N S54370 B3 A1.