Boxes opened, unused. The SIEMENS SIMATIC S7-300 SM321 is a digital PLC input module specifically designed for the Simatic S7 controller platform. It is manufactured in Germany by Siemens, a well-known brand in the industrial automation and motion controls industry. This module is programming-free and can handle various data types, making it a versatile and reliable choice for complex control systems in various business, office, and industrial settings. Its compact and sturdy design, as well as its compatibility with the S7/300 platform, make it a valuable asset for automating processes with precision and efficiency.