Allen-Bradley 1747-L542 SLC 5/04 Processor Module Overview

Product Introduction

When your control system needs reliable mid-range processing, the Allen-Bradley 1747-L542 delivers. This SLC 5/04 processor module is part of the SLC 500 family by Rockwell Automation. It handles up to 4096 discrete inputs and 4096 discrete outputs, with 480 analog I/O points. The 1747-L542 offers 32 KB of battery-backed RAM memory, ensuring program retention during power loss. Its built-in RS-232 and Data Highway Plus (DH+) communication ports enable seamless integration with HMIs, SCADA systems, and other Allen-Bradley PLCs like PLC-5, CompactLogix, and ControlLogix.

Technical Specifications

The 1747-L542 includes a memory capacity of up to 32 KB, supported by battery-backed RAM. The battery backup uses a 1747-BA battery, which maintains the program data when the system is powered down. This processor module operates with a program scan time of 0.9 ms per K of logic and an I/O scan time of 0.225 milliseconds. It supports up to 3 local I/O chassis with a maximum of 30 slots. The backplane current draw is 1 A at 5 VDC and 175 mA at 24 VDC. Ambient temperature range is 0 to 60 degrees Celsius.

Industry Applications

Manufacturing facilities use the 1747-L542 for machine control, material handling, and process automation. Its 4096 I/O capacity suits medium-sized assembly lines where multiple sensors and actuators require coordinated logic. The DH+ port allows real-time data exchange with supervisory systems, making it effective for batch processing and packaging applications. In water treatment plants, the processor manages pump sequencing and tank level monitoring, leveraging its analog I/O for precise control.

Installation & Setup Guidance

Install the 1747-L542 in slot zero of any SLC chassis such as the 1746-A2, 1746-A7, 1746-A10, or 1746-A13. The processor receives power through the backplane from the system power supply located at the leftmost chassis position. Use the key switch on the front panel to select the operating mode: Run, Program, or Remote. Connect the RS-232 port to a programming terminal or HMI for configuration. The DH+ port links to other DH+ devices for network communication. Ensure the battery (1747-BA) is installed and connected before powering up to preserve memory.

Maintenance & Reliability

Periodically check the front panel LEDs for status: Run, CPU Fault, Forced I/O, Battery Low, RS-232, and DH+. A low battery LED indicates the need to replace the 1747-BA battery. Keep the ambient temperature within 0 to 60 degrees Celsius and relative humidity between 5% and 95% non-condensing. The processor withstands 30G operating shock and 2.5G vibration at 57 to 2000 Hz. Regular inspection of the backplane connections and chassis slots helps prevent intermittent faults. For complete technical specifications for the 1747-L542, please contact BluePLC Industrial.

Compatibility & Integration

The 1747-L542 works with all SLC 500 modular hardware including 1746 I/O modules. It communicates via DH+ and RS-232, allowing integration with Rockwell Automation PLCs and third-party devices. Use the DH+ port for peer-to-peer messaging or pass-through communication to ControlLogix and CompactLogix controllers. The RS-232 port supports programming software like RSLogix 500. This processor is compatible with 1746-A2, 1746-A7, 1746-A10, and 1746-A13 chassis.

Selection Guide & Purchasing Advice

Before purchasing the 1747-L542, verify your system's I/O requirements and chassis slot count. Confirm that your power supply can support the backplane current draw of 1 A at 5 VDC and 175 mA at 24 VDC. Order the 1747-BA battery separately if not included. BluePLC Industrial offers this processor with reliable availability and support. Contact BluePLC Industrial for current lifecycle status and replacement options.