SIMATIC S7-300, digital input SM 321, electrically isolated, 16 DI, DC 24V, 1x 20-pin SIMATIC ET 200M is a modular and universally applicable I/O system for the control cabinet in IP20, which can be used both as a central I/O on an S7-300 and in a decentralized configuration on a PROFINET or PROFIBUS ET 200M interface module. Up to 12 IO modules can be plugged into each station. The standardized structure of all modules makes logistics and spare parts management significantly easier. ET 200M can be used for both standard and safety-related applications. Up to 12 high-channel signal (e.g. 64 digital inputs) and function modules as well as communication processors of the S7-300 can be used as I/O modules (the interface to the process). The ET 200M also supports modules with extended user data, such as HART modules with HART auxiliary variables. For easy wiring, the ET 200M offers you the Fast Connect quick connection technology, which does not require stripping, in addition to conventional connection technologies.