BLOG · May 2026

Allen Bradley PLC Surplus Values: SLC, MicroLogix, ControlLogix

By Sean Rupley, Industrial Surplus World · 30+ years in the industry

Allen Bradley PLC Surplus Values: SLC, MicroLogix, ControlLogix

When it comes to buying or selling industrial automation equipment, understanding Allen Bradley PLC surplus values: SLC, MicroLogix, ControlLogix is critical for making informed decisions. With over 30 years of experience in industrial controls, I’m Sean Rupley from Industrial Surplus World, here to provide you an in-depth guide to the surplus market for these popular Allen Bradley PLC product lines. Whether you are a seller trying to maximize your return or a buyer seeking reliable, cost-effective automation solutions, knowing the market dynamics, condition grading, and real-world values of these controllers can make all the difference.

Understanding Allen Bradley PLC Product Lines: SLC, MicroLogix, and ControlLogix

Allen Bradley, a Rockwell Automation brand, is a leading manufacturer of programmable logic controllers (PLCs) widely used across manufacturing, process control, and heavy industry. Their three most common lines in the surplus market are:

Each product line has a unique market value profile in the surplus industry based on availability, demand, legacy system compatibility, and condition. Let’s explore these in detail.

SLC 500 Surplus Values: Legacy Workhorses with Steady Demand

The Allen Bradley SLC 500 series, including popular processors like the 5/03, 5/04, and 5/05, has been a staple for decades. Despite its age, many plants still operate SLC systems, making SLC PLCs a steady seller in the surplus market.

Common SLC Modules and Real-World Prices

ModelDescriptionTypical Surplus Price Range (USD)
1747-L532 (SLC 5/03)Processor with 32K memory$350 - $600
1747-L543 (SLC 5/04)Processor with 64K memory$450 - $800
1747-OB1616-point output module$80 - $150
1747-IB1616-point input module$70 - $140

Values fluctuate based on model, condition, and included accessories such as communication modules (1747-ASB, 1747-SN). Genuine Allen Bradley units with Rockwell Automation firmware versions matching legacy software (RSLinx, RSLogix 500) command premium prices.

Condition Grading for SLC Units

MicroLogix Surplus Values: Compact Controllers with Expanding Applications

MicroLogix PLCs serve a broad range of smaller automation tasks and have grown in popularity due to their compact footprint and versatile I/O options. MicroLogix 1000, 1100, 1200, and 1400 series are the dominant models you’ll encounter.

Typical MicroLogix Surplus Price Points

ModelDescriptionTypical Surplus Price Range (USD)
1761-L16BWA (MicroLogix 1000)10 input / 6 output, onboard basic I/O$150 - $300
1763-L16BWA (MicroLogix 1100)Expanded memory, Ethernet port$300 - $500
1762-L24BWA (MicroLogix 1200)Higher I/O count, supports optional expansion$350 - $600
1766-L32BXB (MicroLogix 1400)Largest onboard I/O, Ethernet and serial comms$500 - $800

MicroLogix controllers retain strong resale value due to ongoing support from Rockwell Automation and their efficiency in small-scale machine control. Ethernet-enabled models (1100, 1400 series) command higher prices owing to modern connectivity requirements.

Tips for Sellers of MicroLogix PLCs

ControlLogix Surplus Values: High-End Modular Automation Controllers

The Allen Bradley ControlLogix platform is the premier choice for complex automation systems requiring scalability and reliability. These systems use the 1756 series chassis, processors, I/O modules, and communication cards.

Popular ControlLogix Models and Price Ranges

ModelDescriptionTypical Surplus Price Range (USD)
1756-L61 (ControlLogix 5571 processor)High-performance CPU, 1MB memory$1,200 - $2,000
1756-L72 (ControlLogix 5572 processor)Enhanced speed, 2MB memory$1,800 - $3,000
1756-IB16 (Input module)16 points, 24V DC input$250 - $400
1756-OB32 (Output module)32 points, relay or transistor outputs$300 - $500

Factors Affecting ControlLogix Surplus Values

Practical Advice for Sellers to Maximize Your Allen Bradley PLC Surplus Value

Whether you are unloading legacy inventory or upgrading your plant automation, here are proven strategies to get the best market return on your Allen Bradley PLC surplus:

  1. Inventory and Document Everything: Record exact model numbers, serial numbers, firmware versions, and condition notes. Buyers want detailed specs.
  2. Test and Refurbish: Invest time in cleaning, testing, and repairing units. Certified working condition increases value dramatically.
  3. Include Accessories: Power supplies, communication cables, manuals, and software licenses add significant value.
  4. Grade Your Stock: Separate items into new, refurbished, working used, and for parts categories to set realistic price expectations.
  5. Monitor Market Demand: Use online surplus marketplaces, industrial auctions, and direct buyer inquiries to gauge pricing trends.

For example, a tested and clean 1747-L543 SLC 5/04 processor with a 1747-ASB communication module and power supply bundle can fetch $900-$1,200, compared to $450 if sold alone and untested.

Where to Sell or Buy Allen Bradley PLC Surplus Equipment

Industrial Surplus World offers a nationwide buying and selling platform with over three decades of expertise. Visit our homepage to browse inventory or list your surplus equipment. For personalized consultation, please reach out via our contact page.

Additionally, Rockwell Automation maintains an official resource page featuring detailed specs and product lifecycle information which is invaluable for verifying model compatibility and end-of-life status: Rockwell Automation Allen Bradley PLCs.

Frequently Asked Questions (FAQ)

1. How do I determine the condition grading of my Allen Bradley PLCs?

Condition grading involves inspecting the physical and functional status of the PLC and modules. New surplus is unopened and unused; refurbished units have been cleaned, tested, and repaired; used units are operational but show wear; for parts means units are non-functional or incomplete. Testing software communication and I/O functionality is essential to accurate grading.

2. Are Allen Bradley MicroLogix PLCs still supported by Rockwell Automation?

Yes, Rockwell continues to provide technical support, firmware updates, and software compatibility for MicroLogix 1100 and 1400 series. However, older MicroLogix 1000 and 1200 models are considered legacy but still widely used and supported by third-party vendors.

3. What factors most influence ControlLogix surplus values?

Processor model and memory size, firmware version, included modules (I/O, communication, specialty), and overall condition are key. Modules with Ethernet or high-speed capabilities command higher prices. Also, having original documentation and tested operational status adds value.

4. Can I sell Allen Bradley PLCs that are no longer supported by the manufacturer?

Yes, many industrial users operate legacy Allen Bradley PLCs and seek surplus units for maintenance and expansion. While unsupported models may have lower value, certain rare or discontinued units can be highly sought after for replacement parts or specific applications.

5. How can I verify the authenticity of Allen Bradley PLC surplus units?

Look for Rockwell Automation part numbers, serial numbers, and date codes. Genuine units will have clear labeling and often come with original packaging or manuals. Beware of counterfeit or refurbished parts without proper documentation. Purchasing from reputable suppliers like Industrial Surplus World ensures authenticity.

Conclusion

Understanding Allen Bradley PLC surplus values: SLC, MicroLogix, ControlLogix requires detailed knowledge of model specifications, condition grading, and current market demand. With over 30 years in industrial controls, Industrial Surplus World is your trusted partner for buying and selling Allen Bradley PLC equipment

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