SIMATIC S7-300, Digital Input SM 321, isolated potential, 16 DI, DC 24V, 1x 20-pin, process alarm, diagnostics, suitable for synchronous operation. SIMATIC ET 200M is a modular and universally applicable peripheral system for the control cabinet in IP20, which can be used both as central peripheral equipment for an S7-300 and in a decentralized setup with a PROFINET or PROFIBUS ET 200M interface module. Up to 12 I/O modules can be plugged in per station. The standardized design of all modules significantly simplifies logistics and spare parts management. ET 200M is suitable for both standard and safety-related applications. As peripheral components (the interface to the process), 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. Thus, the ET 200M also supports modules with extended payload data, such as HART modules with HART secondary variables. For easy wiring, the ET 200M offers the Fast Connect technology for tool-free connections in addition to conventional connection techniques.