Allen-Bradley 1766-L32BWA MicroLogix 1400 32-Point Controller 120/240V AC

A 32-point MicroLogix 1400 controller powered from AC

The Allen-Bradley 1766-L32BWA is a MicroLogix 1400 programmable controller with 20 embedded 24V DC inputs and 12 relay outputs, powered from a 100 to 240V AC supply. It has an LCD display with a keypad and a built-in EtherNet/IP port, so it can be monitored and programmed without extra modules.

It is usually chosen for compact machines that need fast counting inputs, a handful of relay outputs and the ability to grow with 1762 expansion modules.

Technical specifications

Reading the catalog number 1766-L32BWA

1766 is the MicroLogix 1400 family and L32 indicates 32 embedded points. The manufacturer table pairs the BWA code with 100/240V AC power, 24V DC inputs and 12 relay outputs; the letters themselves are not defined in the document. A catalog number with a second trailing A, such as 1766-L32BWAA, adds four analog voltage inputs and two analog voltage outputs.

The matching 24V DC-powered model with six relay and six transistor outputs is the 1766-L32BXB, listed separately.

Inputs, outputs and power

Inputs 0 to 11 are high-speed and accept 4.5 to 24V DC at up to 100 kHz. Inputs 12 and above are standard 10 to 24V DC inputs up to 1 kHz. Each relay output is rated 2.5 A continuous, with 1440 VA as the maximum controlled load.

A 24V DC user supply at 250 mA is available on this AC model for sensors. The expansion bus supports up to seven 1762 modules. Operating temperature is -20 to +65 °C and the controller is open-style, so it must be installed in a suitable enclosure.

Keep power and signal wiring routed separately, following the wiring categories printed in the manual, which are category 2 for signal and power ports and category 3 for communication ports.

Key features of the MicroLogix 1400 platform

• Built-in LCD and keypad: view and change data table values, check I/O status and see faults without a laptop, which is handy on remote skids.
• Three communication ports: EtherNet/IP for HMI and SCADA, plus two serial ports for Modbus RTU or DF1 devices, modems and older panels.
• High-speed inputs: twelve inputs rated up to 100 kHz for flow meter pulses, encoders and fast counting.
• Relay outputs: isolated contacts that can switch AC or DC loads such as contactor coils, solenoid valves and indicator lamps.
• Expansion: up to seven 1762 modules for additional digital, analog, RTD or thermocouple I/O.

Choosing between 1766-L32BWA and related catalog numbers

The MicroLogix 1400 family shares the same processor and communication ports; the differences are power supply, output type and analog I/O. The BWA version suits panels with an AC supply that need relay outputs. Where analog signals such as 4–20 mA or 0–10 V are needed and only a few channels are involved, the 1766-L32BWAA with embedded analog I/O may save an expansion module. Where fast switching outputs or PWM are required, the transistor output variants are a better match, because relay contacts are not suited to high switching rates.

Relay output practice

Relay contacts have a finite electrical life that depends on load current and type. Inductive loads such as solenoids and contactor coils produce arcing on opening, so fit suitable suppression (RC networks or diodes on DC coils) across the load. For loads that switch many times a minute, use an interposing solid-state relay or a transistor output controller to avoid wearing out the on-board relays. Respect the per-channel and common rating listed above when grouping loads.

Programming and networking

The controller is programmed with RSLogix 500 or Connected Components Workbench, depending on the software version in use. The EtherNet/IP port supports messaging to other Rockwell controllers and HMIs, and the serial ports are commonly used for Modbus RTU links to energy meters, VFDs and remote I/O. Keep a copy of the program and note the firmware revision; it simplifies like-for-like replacement.

Installation in Oman and GCC conditions

The operating range of –20 to +65 °C is generous for a compact PLC, but panel interiors in summer sun can approach that limit. Provide shading, ventilation or panel cooling, mount the controller on DIN rail or panel with the clearances in the installation instructions, and keep it away from heat-producing drives and transformers. In dusty sites use a sealed enclosure with filtered ventilation. Typical uses in the region include water pumping stations, package treatment plants, small compressor and chiller panels, conveyor control and building services.

What to include in an RFQ

Please give the catalog number 1766-L32BWA, quantity, required series if your panel documentation specifies one, and any 1762 expansion modules, memory module or communication cables needed. If you are replacing an installed unit, include a photo of the label so the series and firmware can be matched.

Documents and quotation

The MicroLogix 1400 installation instructions 1766-IN001 hold the specification tables, terminal layouts and certifications. For a quotation send the 1766-L32BWA reference, quantity and series. Confirm the exact catalog number before ordering, because the BWAA and AWA models are different products. Related items are in PLC & I/O Cards.