MicroLogix 1400

The Allen-Bradley MicroLogix 1400 (Bulletin 1766) is a compact, fixed-I/O programmable logic controller offering 32 on-board discrete I/O points in a single housing, with optional embedded analog expansion. Decoding the catalog number reveals the controller's full configuration at a glance: the -L32 suffix identifies the 32-point discrete I/O base; the first letter following (-L32A or -L32B) indicates input voltage — A for 120V AC inputs, B for 24V DC inputs; the next character (W or X) defines output type — W for relay-only outputs, X for relay plus FET transistor outputs supporting PTO/PWM up to 40 kHz; and the trailing letter denotes supply power — A for 100/240V AC, B for 24V DC. Appending an additional A (e.g., L32BWAA) adds four analog voltage inputs and two analog voltage outputs to the base unit. The 1766-MM1 memory module is a key accessory, enabling program backup and transfer without a connected PC. Full wiring, configuration, and I/O specifications are documented in the MicroLogix 1400 User Manual (1766-UM001).