Allen-Bradley 1766-L32BXB MicroLogix 1400 32-Point Controller 24V DC

The 24V DC-powered MicroLogix 1400 with mixed outputs

The Allen-Bradley 1766-L32BXB is a MicroLogix 1400 controller powered from 24V DC, with 20 digital inputs and a mixed output set of six relay outputs and six DC transistor outputs. Three of the transistor outputs are fast and three are normal, which suits pulse or high-speed positioning tasks.

It is the DC-supply choice for panels that already have a 24V DC rail, or for mobile and skid-mounted equipment.

Technical specifications

What differs from the AC model

The 1766-L32BWA takes 100 to 240V AC and has 12 relay outputs plus a 24V DC sensor supply. This 1766-L32BXB takes 24V DC and has no sensor supply, but gives six relay outputs and six FET outputs. The input set of twelve high-speed and eight standard DC inputs is the same.

Power consumption is stated as 50 W in full configuration and 7.5 W with no expansion I/O. The relay load limit is 1080 VA, lower than the 1440 VA of the AC model.

Output behaviour and ports

General-purpose FET outputs need at least 1.0 mA of load and tolerate a 4.0 A surge for 10 ms. The high-speed outputs 2, 3 and 4 are limited to 100 mA with a 20 mA minimum load. Relay outputs are rated 2.5 A per channel.

The controller has an RS-232/RS-485 combo port, a built-in EtherNet/IP port and a D-shell RS-232 port. It accepts up to seven 1762 expansion modules. The family image shown is not this exact catalog number.

Panel mounting follows the usual MicroLogix 1400 practice: the controller can be fixed to a DIN rail or screwed to a panel, spacing around the housing is specified in the manual, and the unit is open-style so it belongs inside a cabinet. A replaceable 1747-BA battery is fitted, and the LCD shows a battery-low indicator. Shock is 30 g in panel mounting.

Key features at a glance

• 32 embedded I/O points: 20 DC inputs, 6 relay outputs and 6 FET outputs on one compact base unit.
• Built-in EtherNet/IP: the RJ45 port supports programming, HMI connection and peer messaging without an add-on card.
• Two serial channels: the RS-232/RS-485 combo port and the second RS-232 port allow Modbus RTU, DF1 or DH-485 links to drives, meters and legacy panels.
• LCD display and keypad: the built-in display lets technicians view I/O status and data values and change selected values without a laptop.
• Expandable: up to seven 1762 modules add analog, thermocouple, RTD or extra digital points.

Typical applications

The DC supply and fast transistor outputs make the 1766-L32BXB a common choice for package equipment: dosing skids, small water treatment units, booster pump sets, conveyors, palletisers and HVAC plant rooms. The high-speed inputs can count encoder or flow-meter pulses, and the fast FET outputs can drive stepper or servo drives that accept pulse-and-direction signals. Relay outputs remain useful for contactor coils, solenoid valves and alarm lamps that need voltage-free switching.

Planning the I/O

Because this model has no built-in 24 V sensor supply, proximity switches, photoelectric sensors and transmitters need a separate 24 V DC power supply. Size that supply for the controller, the expansion modules and all field devices together, with headroom for the stated inrush current.

Programming and software

MicroLogix 1400 controllers are programmed with RSLogix 500 or the free RSLogix Micro Starter Lite edition, using ladder logic with the familiar SLC-style file structure. This makes it straightforward to migrate small SLC 500 or MicroLogix 1100 programs. Data logging and recipe functions are built into the controller memory, and online editing allows changes while the machine is running, subject to your site’s change procedures.

Installation and maintenance tips

• Fit the controller in an enclosure with the ventilation clearances given in 1766-IN001; avoid mounting directly above drives or other heat sources.
• Use a Class 2 SELV 24 V DC supply as required by the installation instructions.
• Protect relay outputs switching inductive loads with suitable suppressors, and DC inductive loads with flyback diodes.
• Replace the 1747-BA battery when the battery-low indicator appears, and keep an up-to-date program backup.

Operating in Oman and GCC sites

The -20 to +65 °C operating range gives margin for many outdoor panels, but enclosure temperatures under direct sun in summer can still exceed that limit. Sun shades, light-coloured enclosures, filtered fans or panel air-conditioners are commonly used on skids in Oman. Dust-tight enclosures and sealed cable glands help keep fine sand out of the terminals and the RJ45 port.

What to include in your RFQ

• Catalog number 1766-L32BXB (or 1766-L32BXBA if embedded analog I/O is needed) and quantity.
• Required series or firmware revision if the unit replaces an existing controller.
• Any 1762 expansion modules, end cap, spare 1747-BA batteries and programming cables.
• Delivery location and required documents.

Documents and quotation

The MicroLogix 1400 installation instructions 1766-IN001 hold the tables used here. For a quotation send the 1766-L32BXB reference, quantity and series. Confirm the exact catalog number before ordering, and note that the BXBA type has analog I/O. See PLC & I/O Cards for related products.