Allen-Bradley 1756-L61 ControlLogix Controller

The Allen-Bradley 1756-L61 ControlLogix Processor is a high‑capacity ControlLogix CPU designed for large‑scale automation, featuring 2 MB of user memory for data and logic and a CompactFlash memory card (478 KB) for back‑up storage. Onboard I/O connectivity includes one RS‑232 serial port and a USB interface, while built‑in network options provide EtherNet/IP, ControlNet, DeviceNet, Data Highway Plus, Remote I/O, and SynchLink support to integrate a wide range of field devices. The L61 is part of the ControlLogix 5560/5561 family and supports up to 32 tasks and up to 100 programs per task, with programming languages including Relay Ladder, Structured Text, Function Block, and SFC within the ControlLogix environment. It is designed to operate as a robust processor in complex automation architectures, coordinating logic, sequencing, and motion tasks when used with compatible I/O modules and motion options. As of June 1, 2017, Rockwell Automation discontinued the 1756‑L61, positioning it as a legacy processor best suited for maintenance or retrofit of existing ControlLogix installations rather than new designs.