Overview
The Allen-Bradley 1747-L542 is an SLC 5/04 processor module designed for the SLC 500 modular hardware platform. This mid-range controller offers 32K words of battery-backed user memory (28K for programs, 4K for data) and supports up to 4,096 discrete inputs and 4,096 discrete outputs, with capacity for up to 480 analog I/O points. The processor is engineered for reliable control in manufacturing, packaging, material handling, and process automation applications.
Key Features
- 32K Words User Memory — 28K for program storage, 4K for data retention
- High-Speed Processing — Typical scan time of 0.9 ms/K for responsive real-time control
- Dual Communication Ports — Built-in Data Highway Plus (DH+) and RS-232 DF1 for plant-floor networking and device connectivity
- Battery-Backed RAM with Flash EEPROM — Protects memory during power outages and enables firmware upgrades
- Advanced Math Functions — Trigonometric, PID, exponential, and floating-point calculations
- Keyswitch Mode Selector — RUN, REMOTE, and PROGRAM modes for operational flexibility
- LED Status Indicators — Run, CPU Fault, Forced I/O, Low Battery, RS-232, and DH+ indicators
Technical Specifications
- Processor Series: SLC 5/04
- User Memory: 32K words (32,000 words)
- Program Memory: 28K words
- Data Memory: 4K words
- Max Discrete Inputs: 4,096
- Max Discrete Outputs: 4,096
- Analog I/O Capacity: 480 points
- Instruction Set: 107 instructions
- Scan Time: 0.9 ms/K typical
- Communication Ports: DH+ and RS-232 DF1
- Input Voltage: 5–24 VDC
- Backplane Current: 500 mA @ 5 VDC, 175 mA @ 24 VDC
- Dimensions: 145 mm (H) × 35 mm (W) × 142 mm (D)
- Weight: 0.71 lbs
- Operating Temperature: 0°C to +60°C
- Mounting: Installs in slot 0 of SLC 500 modular chassis
- Certifications: UL listed, CE compliant, C-Tick marked
Typical Applications
- Mid-range manufacturing and assembly line control
- Packaging and material handling equipment
- Process automation with local and remote I/O expansion
- SCADA and HMI integration for factory-wide monitoring
- Peer-to-peer communication with PLC-5, CompactLogix, and ControlLogix controllers via DH+ messaging
- Legacy system upgrades and modernization of SLC 500 deployments
Compatibility & Replacements
Compatible With
- SLC 500 modular chassis (1746-A2, 1746-A7, 1746-A10, 1746-A13)
- SLC 500 I/O modules and power supplies
- Allen-Bradley Remote I/O adapters via DH+ and RS-232
- RSLogix 500 programming software (Studio 5000 Logix Designer not compatible)
- HMI and SCADA systems supporting DH+ and DF1 protocols
- Rockwell ControlLogix and CompactLogix controllers for messaging via DH+
- Modbus RTU master and ASCII protocol support
Replaces / Drop-In Replacement For
- 1747-L542/A (Series A)
- 1747-L542/C (Series C) — with backward compatibility
- Earlier SLC 5/03 processors in equivalent memory class
Works With
- Software: RSLogix 500, Allen-Bradley Programming Software
- Communication Protocols: Data Highway Plus (DH+), DF1 serial, DH-485, ASCII, Modbus RTU master
- Memory Modules: SLC 500 Flash EPROM memory cards
- Recommended Power Supply: 1746-P4 (10 A @ 5V DC, 2.88 A @ 24V DC)
