The Allen-Bradley 1785-L20B is a PLC-5/20 Processor Module, a robust and reliable central processing unit for the Allen-Bradley PLC-5 family of programmable logic controllers. This processor is engineered to manage complex industrial automation tasks, offering 16K words of user memory and extensive I/O capabilities. It features built-in communication ports, including Data Highway Plus (DH+) and a configurable Remote I/O channel, allowing for seamless integration into larger control systems. Designed for durability in demanding industrial environments, the 1785-L20B is a cornerstone of many legacy automation systems, known for its performance and long service life.