Sale!
1747-L552
1747-L552
1747-L552

Allen-Bradley 1747-L552 SLC 5/05 PLC Processor

  • Model: 1747-L552
  • Brand: Allen-Bradley (Rockwell Automation)
  • Series: SLC 500
  • Core Function: PLC program execution and machine control
  • Product Type: CPU / Processor Module
  • Key Specs: 32 KB user memory, integrated Ethernet and RS-232 ports, supports up to 3 local chassis
  • ⚠️ Obsolete Model – Limited Stock Available
  • Condition: New Original / New Surplus
Get a Quote
Categories: , , , , SKU: 1747-L552 Brand:

Description

Key Technical Specifications

Parameter Value
Product Type SLC 5/05 Processor
Manufacturer Allen-Bradley / Rockwell Automation
Model Number 1747-L552
Product Series SLC 500
User Memory 32 KB
Processor Type SLC 5/05 CPU
Communication Ports 10Base-T Ethernet, RS-232 Serial
Supported Protocols EtherNet/IP, DF1 Full Duplex, DF1 Half Duplex, DH-485, ASCII, Modbus RTU Master
Maximum Local Chassis 3
Maximum Local I/O Slots 30
Maximum Digital I/O 4,096 Inputs / 4,096 Outputs
Maximum Analog I/O 480 Points
Program Scan Time Approximately 0.9 ms per 1 K program
I/O Scan Time Approximately 0.225 ms
Memory Backup Battery-backed RAM with optional Flash memory module
Operating Temperature 0 to 60 °C
Storage Temperature −40 to 85 °C
Relative Humidity 5–95% non-condensing

The 1747-L552 is a discontinued SLC 5/05 controller featuring 32 KB memory with integrated Ethernet and RS-232 communications. It remains widely deployed in legacy manufacturing systems requiring Ethernet connectivity without migrating to newer PLC platforms.

 

Product Introduction

The Allen-Bradley 1747-L552 is a 32 KB SLC 5/05 processor developed for the SLC 500 control platform. It executes ladder logic, manages local I/O, and provides both integrated Ethernet and RS-232 communication for programming, HMI integration, SCADA connectivity, and peer-to-peer messaging.

From years of supporting legacy production lines, the Ethernet interface is the primary reason many facilities continue using the 1747-L552. Plants that upgraded their supervisory networks while retaining proven SLC 500 control logic often selected this processor because it reduced the need for external communication gateways.

1747-L552

1747-L552

1747-L552

1747-L552

Installation & Configuration Guide

Stage 1 – Pre-Installation Preparation (Estimated Time: 10 Minutes)

⚠️ Safety First

  1. Notify production personnel of the planned shutdown.
  2. Place all controlled equipment in a safe operating condition.
  3. Apply lockout/tagout procedures.
  4. Remove chassis power.
  5. Wait at least 5 minutes before opening the control cabinet.

Tools Required

  • Grounded ESD wrist strap
  • PH1 screwdriver
  • Fluke 115 digital multimeter
  • Wire identification labels
  • Smartphone for documenting wiring

Data Backup

  1. Upload the complete RSLogix 500 project.
  2. Save processor data tables.
  3. Record Ethernet IP address, subnet mask, and gateway.
  4. Record RS-232 Channel 0 configuration.
  5. Photograph communication cables.
  6. Verify battery condition.
  7. Check for an installed Flash memory module.

Stage 2 – Removing the Existing Processor (Estimated Time: 10 Minutes)

  1. Confirm chassis power is OFF.
  2. Disconnect Ethernet and serial cables.
  3. Label all communication wiring.
  4. Release the processor locking tabs.
  5. Remove the processor using straight, even pressure.
  6. Inspect the backplane connector for bent pins, oxidation, or debris.

⚠️ Do not dispose of the original processor until the replacement has completed commissioning successfully.

Stage 3 – Installing the New Processor (Estimated Time: 10 Minutes)

  1. Wear a grounded ESD wrist strap.
  2. Verify the replacement catalog number is 1747-L552.
  3. Install the battery and Flash memory module if required.
  4. Insert the processor fully into the chassis.
  5. Confirm both locking tabs engage.
  6. Reconnect Ethernet and RS-232 cables.
  7. Restore the saved application and communication settings.

Self-Checklist

  • Correct processor installed
  • Battery verified
  • Flash memory installed (if applicable)
  • Ethernet cable connected
  • Serial cable connected
  • Processor fully seated

Stage 4 – Power-On & Testing (Estimated Time: 15 Minutes)

Pre-Power Checks

  • Verify chassis power supply voltage.
  • Confirm Ethernet cable integrity.
  • Measure grounding continuity.

Commissioning Procedure

  1. Energize the SLC chassis.
  2. Observe processor LED startup sequence.
  3. Verify the CPU enters RUN mode.
  4. Connect through Ethernet using RSLogix 500.
  5. Confirm the processor IP address.
  6. Verify communication with the HMI and SCADA system.
  7. Execute controlled I/O testing before returning production to service.

⚠️ Troubleshooting Notes

  • FLT LED ON: Verify battery condition, Flash memory compatibility, and diagnostic codes.
  • Ethernet unavailable: Check IP address conflicts, subnet mask, switch port status, and Ethernet cable.
  • Serial communication failure: Verify DF1 settings and serial cable wiring.
  • Processor fault after download: Confirm firmware revision compatibility and correct project file.

Common Field Pitfalls

❗ Firmware Revision Differences

I’ve seen maintenance teams install a spare processor from warehouse inventory only to discover its firmware revision differed from the original. Ethernet messaging instructions behaved differently after startup, resulting in intermittent HMI communication. Record the original firmware before replacing the processor.

❗ Ethernet Address Conflicts

This catches experienced engineers more often than beginners. If the replacement processor retains an old IP configuration, the network may experience duplicate IP conflicts. Always verify the configured address before reconnecting the Ethernet cable.

❗ Flash Memory Assumptions

Some replacement processors include a Flash memory module containing another customer’s application. Before powering the system, confirm whether the processor will boot from Flash or RAM. Loading the wrong project can stop production immediately.

❗ Backplane Power Capacity

The 1747-L552 consumes substantially more backplane current than earlier SLC processors. Before adding analog or specialty modules, calculate total chassis loading and maintain at least a 20% reserve. A marginal power supply often causes intermittent faults that resemble communication problems.

❗ Electrostatic Discharge

Always install the processor on a grounded ESD surface while wearing a wrist strap. Static damage frequently affects Ethernet interface circuitry long before any visible damage appears.

Keep these checks in mind and you’ll eliminate most commissioning issues before production resumes.

 

Frequently Asked Questions (FAQ)

Q1. Is the Allen-Bradley 1747- obsolete?

Yes.

Rockwell Automation announced the 1747- SLC 5/05 32 KB Controller as discontinued, with availability ending on March 31, 2024. Existing installations continue to be supported through repair services and replacement inventory.

Q2. Can I replace the 1747- without shutting down the PLC?

No.

The processor is not hot-swappable. Removing it while the chassis is energized can damage the backplane and interrupt every I/O module in the rack.

Q3. Will replacing the processor erase my PLC program?

Not if proper backups exist.

Upload the complete RSLogix 500 project before removing the processor. If a Flash memory module is installed and configured correctly, recovery is faster, but never rely on it without verification.

Q4. Why is the 1747- still widely used?

Unlike earlier SLC processors, the 1747- includes native Ethernet connectivity in addition to RS-232 communications. That allows direct integration with many HMIs, SCADA systems, historians, and engineering workstations without requiring an external Ethernet gateway.

Q5. What is the recommended replacement if this processor is unavailable?

For minimum downtime, another remains the most straightforward replacement. For long-term modernization, Rockwell recommends an engineering migration to current ControlLogix or CompactLogix platforms rather than a direct hardware substitution.

Q6. Why are New Surplus processors typically less expensive than the original OEM list price?

Most New Surplus inventory comes from canceled automation projects, plant expansions, or warehouse stock that was never installed. Pricing reflects lifecycle status rather than processor capability. Always verify inspection records, firmware revision, warranty coverage, and functional test reports before purchase.

Q7. How is each 1747- processor inspected before shipment?

Each processor should complete a documented inspection process:

  1. Inbound Inspection & Traceability
    • Verify OEM labels and serial numbers.
    • Inspect for corrosion, repairs, connector wear, and UV discoloration.
  2. Functional Testing
    • Install the processor in a genuine SLC 500 chassis.
    • Verify LED startup sequence.
    • Test Ethernet and RS-232 communications.
    • Download and execute a validation application.
    • Operate continuously for more than 24 hours while monitoring communication stability.
  3. Electrical Testing
    • Perform insulation resistance testing using a 500 V Megger.
    • Verify ground continuity.
    • Complete dielectric testing where applicable.
  4. Firmware & Configuration Verification
    • Record firmware revision.
    • Verify battery condition.
    • Confirm Flash memory operation and communication settings.
  5. Final QC & Packaging
    • QC inspector approval.
    • ESD protective packaging.
    • Heavy-duty corrugated shipping carton.
    • QC Passed label with inspection date.

Test photographs and operational videos should be available upon request as part of the inspection record.

Related products