Product Overview: Allen-Bradley 1747-L542/B
The Allen-Bradley 1747-L542/B is a processor module from the SLC 500 / Bulletin 1747 series. It functions as the central controller for modular SLC 500 systems. Specifically, this unit is the SLC 5/04 processor with 32K words of user memory. It provides integrated RS-232 and Data Highway Plus (DH+) communication ports. Therefore, it installs in slot 0 of a 1746 chassis. This module is discontinued as of March 31, 2024. Rockwell Automation recommends migration to the 5380 platform as an engineering replacement.
Key Technical Specifications
Engineers select the 1747-L542/B for its exact memory and communication configuration. The table below summarizes verified parameters from official manufacturer data.
- User Memory: 32K words
- Communication Ports: RS-232 and DH+
- Maximum I/O: 4096
- Backplane Current: 1A at 5V DC; 175 mA at 24V DC
- Scan Time: 0.9 ms/K
- Operating Temperature: 0 to 60 C
Notably, the 1A at 5V DC backplane draw demands careful power budgeting. The 1746 chassis supplies 5.1V DC at 10A total. Consequently, each module's load must be summed to avoid overcurrent. Additionally, the 175 mA at 24V DC draw affects the 24V DC at 2.88A bus. These precise electrical specifications ensure reliable system design.
Installation and Configuration
Install the 1747-L542/B in slot 0 of a 1746 chassis. The chassis models include 1746-A4, -A7, -A10, and -A13 with 4, 7, 10, or 13 slots. All chassis are panel-mount. However, this processor is not hot-swappable. Therefore, never install, remove, or wire the module with power applied. Always remove power before any physical intervention. Field wiring uses removable terminal blocks. For pre-wired interface options, Bulletin 1492 is available. After installation, verify that the backplane power budget accommodates the 1A at 5V DC and 175 mA at 24V DC loads.
Communication and Integration
The 1747-L542/B includes RS-232 and DH+ ports for programming and peer-to-peer networking. RS-232 supports local configuration and programming. DH+ enables high-speed data exchange on a token-passing network. However, these are legacy protocols. Integrating this processor into modern Ethernet-based systems may require an external gateway or connection module. Therefore, confirm cable and gateway compatibility with your supplier. The processor supports up to 4096 I/O points. This capacity suits mid-range discrete and process control applications. Nevertheless, always verify network topology and termination for DH+ segments.
Maintenance and Lifecycle
Periodic inspection of the processor and chassis connections is recommended. Check for dust accumulation and secure terminal blocks. The operating temperature range is 0 to 60 C with 5-95% RH non-condensing. Consequently, ensure the enclosure maintains these conditions. Since the 1747-L542/B is discontinued, spare units may become scarce. Plan migration to the 5380 platform to avoid unplanned downtime. For current lifecycle status and availability, contact AutoDCSTech before ordering.
Availability & Condition at AutoDCSTech
| Part Number | 1747-L542/B |
|---|---|
| Availability | In Stock |
| Condition | New |
| Warranty | One Year |
| Origin | US |
