1764-24AWA Allen-Bradley MicroLogix 1500 24-Point Base Unit

Product Overview

The 1764-24AWA (176424AWA) serves as the high-density foundational base for the Allen-Bradley MicroLogix 1500 controller system. This 120/240 VAC powered unit features 24 integrated I/O points, specifically designed to bridge the gap between compact micro-PLCs and larger modular systems. Ideal for distributed control in wastewater management, pharmaceutical secondary packaging, and precision assembly lines, the 1764-24AWA provides the essential power supply and I/O interface required to support a 1764-LRP or 1764-LSP processor. By decoupling the processor from the I/O base, this architecture allows for rapid maintenance and upgrades with zero rewiring, significantly lowering the Total Cost of Ownership (TCO) and reducing critical system downtime.

Technical Configuration

The 1764-24AWA utilizes a split-architecture design where the base unit contains the power supply, input/output circuitry, and expansion ports. It is equipped with 12 isolated 120 VAC inputs and 12 relay outputs, making it natively compatible with high-voltage field devices without requiring interposing relays. The unit features an integrated expansion port that supports up to 16 Compact I/O (1769 series) modules, allowing for massive scalability. The internal power supply is engineered to handle industrial-grade voltage fluctuations, while the relay outputs are rated for heavy-duty cycling, ensuring long-term mechanical reliability in high-vibration or high-cycle environments.

Technical Specifications

Technical FAQs

Can I operate the 1764-24AWA base unit without a processor module?

No. The 1764-24AWA is a base unit only. It requires a 1764-LSP or 1764-LRP processor module plugged into the front interface to function as a complete programmable logic controller.

What is the maximum output current rating for the relay contacts?

The relay outputs on the 1764-24AWA are typically rated for a continuous current of 2.0 A per point, with a maximum controlled load of 1440 VA for AC. Always verify your specific inductive load requirements against the NEMA ICS ratings provided in the manual.

Is it possible to mix AC and DC expansion modules with this AC base?

Yes. While the base unit uses 120 VAC inputs, you can add 1769 series Compact I/O expansion modules (Digital DC, Analog, or Thermocouple) to the right side of the unit to accommodate diverse field signal requirements.

Engineering & Installation Guide

• Processor Hot-Plugging Warning: Never attempt to install or remove the 1764-LSP/LRP processor module while power is applied to the 1764-24AWA base. This can cause electrical arcing across the backplane pins, potentially corrupting the processor memory or causing permanent hardware failure.

• Expansion Bus Termination: When expanding the system with 1769 Compact I/O modules, ensure that a 1769-ECR or 1769-ECL end cap is securely installed at the end of the I/O bank. Without the end cap, the I/O bus will remain an open circuit, and the processor will flag a major non-recoverable fault.

• Inductive Load Suppression: Given that this base unit utilizes relay outputs, switching inductive loads (such as motor contactors or solenoids) generates significant Back-EMF. It is mandatory to install MOV (Metal Oxide Varistors) or RC snubbers across AC loads to prevent electromagnetic interference from resetting the internal processor logic.