Siemens 405-12ABM Basic Coprocessor Module

Siemens 405-12ABM Basic Coprocessor Module is a plug-in co-processor for Siemens’ DL405 family of PLCs, designed to reside in a DL405 backplane to supplement the CPU with its own processing path and serial communications capability. The module is built around a 16 MHz clock and provides three serial interfaces for external connectivity: Port 1 supports RS-232C, RS-422, and RS-485 signaling; Port 2 operates as RS-232C or in full-duplex mode; Port 3 is RS-232C. These ports enable connections to modems, printers, terminal devices, and other serial equipment commonly used in industrial automation. As a Basic Coprocessor Module, the 405-12ABM is intended for integration with the DL405 CPU base and ancillary I/O modules within the Siemens Texas Instruments automation ecosystem, supporting serial communication configurations and offloading certain processing tasks from the main controller. This combination is typically employed in legacy 405-series installations where additional processing power and expanded serial I/O are required without replacing the core DL405 hardware, such as in manufacturing lines, packaging, and batch control environments that rely on proven, long‑life equipment.