The Allen-Bradley 1764-24BWA, also cataloged as the 176424BWA Base Unit, operates as a dedicated hardware component for discrete signal processing and field execution within MicroLogix 1500 control architectures.

Functional Configuration Matrix

• 1764-24BWA: Base processing unit providing 120 VAC line power input, 12 sink/source 24 VDC digital inputs, and 12 electromechanical relay outputs.
• 176424BWA: Factory spare part catalog identifier matching the 24-point AC-powered base hardware interface.

Technical Performance Parameters

Bus Communication & High-Speed Processing

The base unit routes input signals to the processor module via an integrated high-speed backplane interface. It features firmware flash compatibility across MicroLogix 1500 logic processors, ensuring synchronized I/O scanning and deterministic network response over EtherNet/IP or DH-485 interfaces. The front high-speed input channels process pulses up to 20 kHz, enabling precise pulse-counting without compromising overall I/O density scaling.

Standard Delivery Hardware

• 1 x 1764-24BWA MicroLogix 1500 Base Unit
• 1 x Protective Terminal Cover Shield
• 1 x DIN-Rail Mounting Latch Assembly
• 1 x Hardware Installation Guide

Mounting & Wiring Specifications

Enclosure and Panel Mounting

• Mount the base unit vertically or horizontally on a standard 35 mm DIN rail or secure it to a grounded metal enclosure panel using M4 screws.
• Maintain a minimum surrounding clearance of 50 mm (2 in) to allow adequate thermal convection and wiring access.

Power and Field Terminal Connections

• Connect AC line power (85-265 VAC) to the labeled power terminal block using copper conductors rated for at least 75 deg C.
• Isolate high-voltage AC output wiring from low-voltage 24 VDC sensor inputs in separate wire runs to prevent signal noise coupling.
• Tighten terminal block screws to a maximum torque of 0.9 Nm (8 lb-in).

Technical Operational FAQs

• What input circuit configurations does the 24 VDC input stage support?

  The 12 digital input channels support both sinking and sourcing wiring topologies depending on the common terminal connection.

• What is the maximum switching frequency for the high-speed input channels?

  Inputs 0 through 3 operate as high-speed counters capable of processing input pulse frequencies up to 20 kHz.

• Can the base unit function without a processor module installed?

  No. The 1764-24BWA is a base unit requiring a 1764 processor module (such as 1764-LSP or 1764-LRP) to execute logic control.

• What voltage ranges can the relay contacts switch safely?

  The output relay contacts accept load voltages ranging from 24 to 125 VDC and 120 to 240 VAC under nominal current limits.

• Does the base unit provide auxiliary 24 VDC power for field sensors?

  Yes. An integrated auxiliary power supply provides 24 VDC output current to power connected field input devices directly.

• Is hot-swapping supported for the attached processor or expansion modules?

  No. Power to the 1764-24BWA must be disconnected prior to inserting or removing the processor module or expansion I/O cables.

• How are the 12 relay outputs isolated across the terminal block?

  The relay output contacts are arranged in multiple isolated groups, allowing separate voltage source connections per common group.

• What wire range is compatible with the screw terminal blocks?

  The integrated screw terminals accept solid or stranded copper wire sizes from 0.2 to 2.5 sq mm (24 to 14 AWG).