A Guide To Allen-Bradley PLCs

Allen-Bradley is globally renowned for its innovative spirit and leadership in adopting cutting-edge technologies early on. With a rich history in developing automated control systems, they now offer a diverse range of controllers to suit any specialised application, regardless of scale, at competitive prices. Presently, Allen-Bradley offers three primary platform families of controllers – the MicroLogix PLCs, ControlLogix PLCs, and CompactLogix PLCs.

MicroLogix PLCs

Introduced in 1994, the MicroLogix PLC family aimed to offer a more compact and cost-effective alternative to the SLC500 series, delivering most of its functionalities. Utilising the RSLogix500 software for programming, this family features limited configurable I/O. The emergence of these PLCs stemmed from increased market competition, prompting Allen-Bradley to act upon customer and industry input. Starting with the MicroLogix 1000, followed by the 1100, 1200, and 1500, this line of small-scale, budget-friendly PLCs culminated in the MicroLogix 1400. The latest addition boasts ethernet capabilities, embedded analog inputs, and high-speed counters. Despite its evolution, the MicroLogix PLC family continues to be widely utilised and supported by Allen-Bradley.

ControlLogix PLCs

The ControlLogix PLC family marked the next phase in PLC evolution, debuting in 1997 and gaining widespread availability by 1999. These new mid-range controllers, although competitively priced, delivered top-notch performance with enhanced processing speeds, 32-bit I/O capabilities, and a pioneering Tag Based Addressing system, a significant upgrade from the SLC500 series’ file-based addressing system. Beyond expanding addressable I/O, the 32-bit architecture broadened registers, extended timer and counter ranges, and boasted augmented memory capacity. Coupled with quicker processing speeds and compatibility with the innovative RSLogix5000 programming software, these PLCs ushered in a new era. The standout model in this lineup, the ControlLogix5580, elevated the game with processing speeds exceeding predecessors by leaps (up to 1 Gbps) and supported ethernet, DH+, DeviceNet, and ControlNet, catering to high data logging needs.

CompactLogix PLCs

The CompactLogix PLC family represents the latest line of PLCs from Allen-Bradley, with the inaugural model debuting in 2006. This series offers top-tier performance at a mid-range price point, a response to the perpetual demand for more cost-effective PLC solutions across product iterations. Featuring two variations for enhanced flexibility, the first iteration is a self-contained unit boasting integrated digital and analog I/O capabilities. The second variant is modular, supporting an SD slot, equipped with an embedded USB port, and offering blazing communication speeds of up to 1 Gbps. Additionally, it provides a memory capacity of up to 10 MB while harnessing the communication advantages inherent in the ControlLogix platform.

You can view Mizen Automation’s full range of Allen-Bradley automation parts here.