Allen-Bradley 1756-L1 ControlLogix Controller is a legacy ControlLogix CPU designed to operate within a ControlLogix backplane, with catalog numbers including 1756-L1, 1756-L1M1, 1756-L1M2, and 1756-L1M3. The 1756-M1 memory module provides 512 KB of expansion memory for 1756-L1 family CPUs, enabling larger programs and data storage in a single rack. This processor is part of the older ControlLogix line and was discontinued in 2009, making it a candidate mainly for legacy systems or training setups. In a typical installation, the L1 serves as the central processor in a ControlLogix chassis, coordinating I/O through compatible modules and a power supply to form a complete automation rack.
