The Allen‑Bradley 1747‑L542 is an SLC 5/04 modular processor from Rockwell Automation's SLC 500 family, offering 32K words of user memory and supporting up to 4,096 discrete I/O points. As the mid-range model in the 5/04 series, it features built-in Data Highway Plus (DH+) and RS-232 communication ports, enabling high-speed peer-to-peer messaging with PLC-5, SLC, and ControlLogix processors.
Item No :
1747-L542Order(MOQ) :
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EXWProduct Origin :
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3KG| Specification | Description |
|---|---|
| Manufacturer | Rockwell Automation (Allen‑Bradley) |
| Model | 1747‑L542 |
| Product Family | SLC 500 / SLC 5/04 Processor |
| Product Type | Modular Programmable Logic Controller |
| User Memory | 32K words (Battery‑backed RAM) – approx. 28K program + 4K data |
| Max Discrete I/O | 4,096 inputs / 4,096 outputs |
| Max Analog I/O | 480 points |
| Local Chassis | Up to 3 chassis / 30 total slots |
| Program Scan Time | 0.9 ms per 1K instructions (typical) |
| Bit Execution (XIC) | 0.37 µs |
| I/O Scan Time | 0.225 ms |
| Built‑in Communication | DH+ (Channel 1), RS‑232 (Channel 0) |
| DH+ Baud Rate | 57.6 kbps or 230 kbps |
| RS‑232 Protocols | DF1 Full‑Duplex, DF1 Half‑Duplex, ASCII, DH‑485 |
| Programming Software | RSLogix 500 / Studio 5000 |
| Backup Memory | 1747‑M13 flash memory module (optional) |
| Battery | 1747‑BA battery for memory retention |
| Backplane Current Draw | 1 mA @ 5V DC |
| Operating Temperature | 0°C to +60°C |
| Protection Class | Open‑type (chassis mount) |
| Dimensions (H x W x D) | 145 x 35 x 142 mm |
| Weight | Approx. 0.31 kg (0.69 lbs) |
| Lifecycle Status | Discontinued (as of December 31, 2021) |
| Model | Description | Typical Application |
|---|---|---|
| 1747‑L541 | SLC 5/04 processor with 16K user memory | Smaller applications requiring less memory |
| 1747‑L543 | SLC 5/04 processor with 64K user memory | Large, complex applications with extensive program logic |
| 1747‑L551 | SLC 5/05 processor with 16K memory and built‑in Ethernet | Migration path requiring native Ethernet connectivity |
| 1747‑L552 | SLC 5/05 processor with 32K memory and built‑in Ethernet | Higher‑memory alternative with Ethernet |
| 1747‑L553 | SLC 5/05 processor with 64K memory and built‑in Ethernet | Large‑scale applications needing Ethernet |
| 1747‑M13 | Flash memory backup module | Non‑volatile program storage |
| 1747‑BA | Replacement battery for memory retention | Battery replacement |
| 1761‑NET‑ENI | Ethernet interface module (external) | Adding Ethernet TCP/IP connectivity to SLC 5/04 |
| 5069‑L306 | CompactLogix 5380 controller | Full migration path; official Rockwell replacement recommendation |
| 1746-NT8 | 1794-IE8XT | 1746sc-INI4i |
| 1756-A13 | 1794-IF2XOF2I | 1769-IF4XOF2 |
| 1756-A17 | 1794-IF4I | 1769-IF8 |
| 1746-NI4 | 1794-IF8IH | 1769-IG16 |
| 1756-A7 | 1746-NO4V | 1746-NO4I |
| 1756-BA1 | 1746-NI8 | 1769-IQ16 |
| 1756-BA2 | 1746-OW16 | 1769-IQ16F |
| 1756-BATA | 1794-IM16 | 1769-IQ32 |
| 1756-BATM | 1794-IM8 | 1769-IQ32T |
| 1756-CFM | 1794-IP4 | 1769-IQ6XOW4 |
| 1756-CN2 | 1794-IR8 | 1769-IR6 |
| 1756-CN2R | 1794-IRT8 | 1769-IT6 |
| 1756-CNB | 1794-IRT8K | 1747-L542 |
Q1: Is the 1747‑L542 still in production?
No. The SLC 5/04 processor family has been discontinued by Rockwell Automation as of December 31, 2021. The entire SLC 500 product family was formally discontinued on March 31, 2024. The 1747‑L542 is now available only through the used/refurbished market.
Q2: What is the user memory capacity of the 1747‑L542?
The 1747‑L542 has 32K words of user memory, with approximately 28K words allocated for program logic and 4K words for data storage.
Q3: What communication ports does the 1747‑L542 have?
The processor has two built‑in ports:
Channel 1 (DH+): Data Highway Plus, supporting 57.6 kbps or 230 kbps for messaging with PLC‑5, SLC, and ControlLogix processors
Channel 0 (RS‑232): Supports DF1 full/half‑duplex, ASCII, and DH‑485 protocols
Q4: Can I replace a 1747‑L542 with a newer processor without rewriting the program?
Within SLC 5/04 family: You can upgrade to 1747‑L543 (64K). The program will run without modification, and RSLogix 500 allows processor type change in the project.
To SLC 5/05: Migration requires verifying communication differences—SLC 5/05 supports native Ethernet but the DH+ pin‑out differs, which can cause communication faults if not addressed carefully.
To CompactLogix: Rockwell Automation recommends migrating to the CompactLogix 5380 platform using the RSLogix 500 to Studio 5000 project converter.
Q5: What programming software is required for the 1747‑L542?
The 1747‑L542 is programmed using RSLogix 500 (or Studio 5000) running on Windows. RSLogix 500 supports the entire SLC 500 family, including SLC 5/01 through SLC 5/05 processors.
The Allen-Bradley 1746-P1 is a rack-mount power supply for the SLC 500 programmable controller family. It accepts 120/240V AC input and provides 2A at 5V DC and 0.46A at 24V DC backplane power, along with a 200 mA user-power output for external sensors.
The Allen‑Bradley 1746‑NI4 is a 4‑channel analog input module for the SLC 500 programmable controller family. It accepts voltage (±10V DC) or current (±20mA) signals from field devices such as pressure transmitters, temperature sensors, and level transducers, converting them into digital values for use in the PLC's control program.
The Allen‑Bradley 1747‑L542 is an SLC 5/04 modular processor from Rockwell Automation's SLC 500 family, offering 32K words of user memory and supporting up to 4,096 discrete I/O points. As the mid-range model in the 5/04 series, it features built-in Data Highway Plus (DH+) and RS-232 communication ports, enabling high-speed peer-to-peer messaging with PLC-5, SLC, and ControlLogix processors.
he Allen‑Bradley 1747‑KFC15 is a ControlNet RS‑232 Interface Module for the SLC 500 platform that acts as a DF1‑to‑ControlNet bridge. It connects SLC 5/03, 5/04, or 5/05 processors to a ControlNet network via the processor's Channel 0 serial port, enabling deterministic data exchange with ControlNet‑capable HMIs, drives, and other controllers.
The Allen‑Bradley 1747‑L541 is an SLC 5/04 modular processor from Rockwell Automation's SLC 500 family, offering 16K words of user memory and supporting up to 4,096 discrete I/O points. It features built-in Data Highway Plus (DH+) and RS-232 communication ports, enabling high-speed peer-to-peer messaging with PLC-2, PLC-5, and ControlLogix processors.
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