Siemens SIRIUS 3SK2 Safety Relay Basic Units From Siemens, the base-Unit SIRIUS 3SK2 range of safety relays for demanding safety applications involving more than one safety function. The 3SK2 basic units offer many inputs and outputs within a narrow unit to meet demanding safety applications with several independent safety functions. Flexible application options are enabled by powerful semiconductor outputs, as well as by expandability with additional 3SK1 output expansions and seamless integration into the main conducting path using 3RM1 Failsafe motor starters. Extensive logic functions are available for assigning parameters to independent disconnections of the fail-safe outputs. The SIRIUS Safety ES engineering software allows easy commissioning and offers extensive diagnostic options. Easy implementation of muting and protective door monitoring, for example, is possible by means of prefabricated logic blocks. Devices in 22.5 mm design with 10 inputs and 2 semiconductor outputs or in 45 mm design with 20 inputs and 4 outputs, all with either screw-type or spring-type terminals (push-in). Extensive accessories such as diagnostics display, sealing covers, push-in lugs for wall mounting and coding pins make handling easier. Output expansions can be used by means of device connectors without additional wiring outlay. Safety is a SIRIUS business.