PLC

Programmable logic controllers run virtually every industrial control system. Enicstra stocks PLC processors, expansion modules, I/O cards, and accessories from Allen-Bradley, Siemens, Mitsubishi, Omron, Schneider Electric, and Beckhoff — including the obsolete and end-of-life part numbers that aren't available through new sales channels.

Inventory covers Allen-Bradley ControlLogix, CompactLogix, MicroLogix, SLC-500, and legacy PLC-5; Siemens S7-200, S7-300, S7-400, S7-1200, and S7-1500; Mitsubishi FX and Q-series; Omron CJ, CS, NJ, and NX; Schneider Modicon Quantum, M340, and M580; plus Beckhoff CX embedded controllers. Each PLC is bench-tested and shipped with our 12-month functional warranty.

PLC replacement is rarely just about model matching — firmware revision, expansion module compatibility, and existing program memory format all matter. Send the OEM part number plus the firmware revision if known, and we'll confirm compatibility with your installed system. Most quote inquiries reply within 1–2 business days.

Facets Filter

PLC

Sorry, no results found.

Suggestions:

Double-check spelling, part number, or keywords
Try different or more general search terms
Browse by category or manufacturer

Need Assistance?

Can’t find the part you’re looking for? Please click the button below to request a quote — our team will respond promptly.

New to Enicstra?

We provide one of the largest selections of industrial automation and electronic components, available and ready to ship worldwide. Whether you’re prototyping or scaling to full production, we’re here to support innovation every step of the way.

At Enicstra, we’re known for:

Wide Product Availability
Reliable and Timely Shipping
Exceptional Service Performance
A User-Friendly, Engineer-Focused Experience

Can't Find The Part You Need?

Send us the part number, manufacturer, quantity, and condition — we'll locate it.

Request a Quote

Buying guide

Choosing PLC components

PLC replacement is one of the highest-risk supply tasks in industrial maintenance — the wrong revision can refuse to load the existing program, an expansion module mismatch can stop the rack from booting, and a discontinued series can force a complete control system redesign. Match the part exactly when keeping the existing program is the goal.

Specifications to confirm before ordering:

Exact part number including suffix (revision letter or hardware series)
Firmware revision installed on the existing unit
Memory size (in some part numbers, memory is encoded in the suffix)
Communication options (Ethernet, serial, fieldbus integrated or as modules)
I/O capacity and expansion module compatibility
Programming software version compatible with the firmware
Power supply requirements (24 VDC, 110/230 VAC)
Environmental ratings (industrial, extended temperature, conformal coating)

Selection patterns by application:

Like-for-like replacement on installed equipment: match part number, suffix, and firmware exactly
Equipment migration (older PLC-5 to ControlLogix): plan for program conversion, not a drop-in swap
Distributed I/O additions: check that the existing PLC firmware supports the new expansion modules
Safety PLC requirement: use safety-rated CPUs and I/O (GuardLogix, S7-1500F, etc.) with appropriate validation

If you're not sure about firmware compatibility, send your existing CPU part number along with your programming software version — we'll confirm whether a direct replacement is possible or if a firmware upgrade is needed first.

Related categories Frequently asked questions

Can you supply discontinued Allen-Bradley PLC-5 or SLC-500 hardware?

Yes. End-of-life Allen-Bradley platforms including PLC-5, SLC-500, MicroLogix 1000/1500, and older ControlLogix modules are some of our most common requests. Many remain in service on plants where migration to current platforms isn't yet economical. Submit the catalog number with a quote request.

Will an L72 ControlLogix replace an L71?

Often yes — but firmware revision matters. The L72 has more memory and a faster processor; programs from an L71 typically load, but verify your RSLogix/Studio 5000 version supports both. Always test the migration in a staged environment first, not on a running production system.

What about Siemens S7-300 versus S7-1500?

These are different generations — not drop-in replacements. S7-1500 uses a different programming environment (TIA Portal) and different I/O modules. For S7-300 replacement, source another S7-300 CPU or plan a migration project. We stock both platforms.

Are PLCs new, surplus, or used?

Most stock is new-old-stock — unused, often in original packaging. Some legacy CPUs come from tested system removals with cleared memory. Each product page lists condition; contact us before purchase if not shown.

Do you include programming cables or software?

Programming cables are sold separately and are common items. Programming software is licensed separately by the manufacturer (Rockwell Studio 5000, Siemens TIA Portal, etc.) — we don't supply software licenses.