Selecting the right PLC is an important step when designing or upgrading an industrial automation system. The Allen-Bradley 1766-L32BWA and 1766-L32BXB are two MicroLogix 1400 controllers that provide onboard digital inputs and outputs for controlling industrial equipment. Although they belong to the same PLC family, their power supply requirements and output arrangements are different.
Understanding these differences can help automation engineers, machine builders and maintenance professionals choose the right controller for their control panel.
Allen-Bradley 1766-L32BWA PLC Overview
The Allen-Bradley 1766-L32BWA is a MicroLogix 1400 PLC designed for industrial automation applications. It operates on a 120/240V AC power supply and provides 20 digital inputs and 12 relay outputs. Its inputs receive signals from compatible field devices, such as sensors, switches and push buttons, while the relay outputs control compatible electrical loads. This model is suitable for applications requiring an AC-powered controller with relay-based output switching.
Allen-Bradley 1766-L32BXB PLC Overview
The Allen-Bradley 1766-L32BXB is another MicroLogix 1400 PLC, but it operates on a 24V DC power supply. Like the 1766-L32BWA, it provides 20 digital inputs, including 12 fast inputs and eight standard inputs. However, its 12 outputs comprise six relay outputs, three fast 24V DC FET outputs and three standard 24V DC FET outputs. This combination supports applications that require both relay switching and electronic control of compatible DC loads.
1766-L32BWA vs 1766-L32BXB: Technical Comparison
| Feature | 1766-L32BWA | 1766-L32BXB |
| Product family | MicroLogix 1400 | MicroLogix 1400 |
| Power supply | 120/240V AC | 24V DC |
| Total digital inputs | 20 | 20 |
| Fast digital inputs | 12 | 12 |
| Standard digital inputs | 8 | 8 |
| Total digital outputs | 12 | 12 |
| Relay outputs | 12 | 6 |
| Fast FET outputs | None | 3 |
| Standard FET outputs | None | 3 |
| Embedded analog I/O | No | No |
| Communication options | Ethernet and serial | Ethernet and serial |
Three Important Differences Between These PLCs
1. Power supply
The first difference is the required power source. The 1766-L32BWA is designed for a 120/240V AC supply, whereas the 1766-L32BXB requires a compatible 24V DC supply.
This distinction matters when designing a new control panel or replacing an existing PLC. The available supply and the manufacturer’s wiring requirements must be checked before selecting a replacement.
2. Output technology
The 1766-L32BWA uses 12 relay outputs. Relay outputs can switch compatible loads within their specified electrical limits.
The 1766-L32BXB combines six relay outputs with six FET outputs. This arrangement provides additional options for electronic switching of compatible DC loads.
Engineers should consider load current, voltage, switching frequency and the type of connected device before choosing between these output configurations.
3. Control panel design
The power supply and output differences can influence the overall control panel design. The selected controller must match the available supply, field wiring, load requirements and intended control functions.
Although both PLCs offer 20 digital inputs and 12 digital outputs, they should not automatically be treated as direct replacements for one another.
Where Can These PLCs Be Used?
Both models can be considered for suitable small-scale industrial automation applications, including:
- Packaging and labelling equipment
- Conveyor systems and material handling
- Assembly and production machinery
- Pump control and machine monitoring
- Automated equipment with digital field signals
- Industrial control panels
The final choice depends on the application’s I/O requirements, electrical design, communication needs and operating conditions.
How to Select the Right Model
Before choosing between the 1766-L32BWA and 1766-L32BXB, review the following points:
- Power source: Determine whether the control panel requires the specified AC supply or a 24V DC supply.
- Output requirements: Establish whether the application needs relay outputs only or a combination of relay and FET outputs.
- Field devices: Confirm the electrical compatibility of all connected sensors, actuators and other loads.
- Existing installation: If replacing a PLC, verify the wiring, program compatibility, communication settings and physical installation requirements.
These checks help reduce compatibility problems during installation and commissioning.
Conclusion
The main difference between the Allen-Bradley 1766-L32BWA and 1766-L32BXB is their power supply and digital output configuration. Both provide 20 digital inputs and 12 digital outputs, but the 1766-L32BWA uses 120/240V AC power with 12 relay outputs, while the 1766-L32BXB uses 24V DC power with six relay outputs and six FET outputs.
Neither controller is the right choice for every application. Comparing the electrical supply, output requirements and machine design will help engineers identify the model that best fits their automation system.
For accurate installation and replacement decisions, refer to the official Rockwell Automation product documentation for the relevant catalog number.
