Allen-Bradley 1772-LS PLC-2/05 Processor | Replacement, Equivalent & Selection Guide
The Allen-Bradley 1772-LS is a small-chassis processor module for the PLC-2 family of programmable logic controllers, manufactured by Rockwell Automation (Allen-Bradley). Designed for discrete control applications, it operates within the PLC-2 Mini-PLC system and communicates via the 1772 I/O chassis backplane. This page serves as a comprehensive replacement and equivalent selection guide for engineers, maintenance teams, and procurement specialists sourcing the 1772-LS or evaluating compatible alternatives.
Selection Background
The PLC-2 platform has reached end-of-life status, making direct procurement of the 1772-LS replacement increasingly challenging. Buyers frequently search for a 1772-LS equivalent, a functional substitute, or a cross-brand alternative to maintain legacy production lines without full system migration. Understanding which modules are true drop-in replacements versus functional equivalents requiring configuration changes is critical to avoiding costly downtime. Konmask specializes in sourcing genuine and compatible PLC-2/05 processor substitutes with full traceability.
Technical Specifications
- Part Number: 1772-LS
- Series: Allen-Bradley PLC-2 Family
- Processor Type: PLC-2/05 Small Chassis Processor
- Memory: 1K words (expandable with memory module)
- I/O Capacity: Up to 128 I/O points (local)
- Scan Time: ~1 ms/K words
- Communication: DH-485 / Data Highway compatible (via adapter)
- Programming Language: Ladder Logic (PLC-2 instruction set)
- Power Supply: Supplied via 1772 chassis backplane
- Operating Temperature: 0°C to 60°C
- Chassis Compatibility: 1772-A1, 1772-A2, 1772-A3, 1772-A4 ⚠️ Key parameter for replacement decisions
- Software: APS (Advanced Programming Software) or 6200 Series
- Certifications: UL, CSA
- Form Factor: Single-slot module
Compatible Replacement & Equivalent Models
1. Direct Drop-in Replacements
These modules are physically and electrically interchangeable with the 1772-LS in the same 1772 chassis without hardware modification:
- Allen-Bradley 1772-LS (refurbished/surplus) — Identical OEM unit; verify firmware revision matches existing program
- Allen-Bradley 1772-LSP — Enhanced version with additional memory; backward-compatible in same chassis ⚠️ Confirm program re-upload required
2. Functional Equivalents
Same PLC-2 family processors with equivalent or superior capability; may require program conversion or chassis adapter:
- Allen-Bradley 1772-LX / 1772-LXP — PLC-2/15 and PLC-2/30 processors; larger memory, same instruction set; chassis-compatible ⚠️ Program re-download required
- Allen-Bradley 1772-QL — PLC-2/20 processor; functional equivalent for medium I/O applications
3. Cross-Brand Alternatives (Migration Path)
For applications where PLC-2 chassis replacement is acceptable; requires full system re-engineering:
- Allen-Bradley MicroLogix 1100 (1763-L16BWA) — Modern Rockwell platform; ladder logic compatible; requires program conversion from PLC-2 to RSLogix 500 ⚠️ Not a drop-in; new I/O wiring required
- Siemens S7-200 / S7-1200 — Cross-brand alternative for new installations; requires full re-engineering
- Mitsubishi FX3U Series — Comparable compact PLC for greenfield replacement projects
⚠️ Note: Always verify chassis compatibility, memory capacity, and I/O addressing before substituting. Contact Konmask engineering support for a free compatibility assessment.
Why Choose the Original 1772-LS Model
- Precision Compatibility: Guaranteed fit within existing 1772-A series chassis with no hardware modification or re-wiring
- Program Integrity: Existing PLC-2 ladder logic programs run without conversion, eliminating re-validation costs
- OEM Certifications: UL/CSA-listed; meets original system safety and compliance documentation requirements
- Proven Reliability: Field-tested in continuous industrial environments; known MTBF performance data available
- Technical Support: Konmask provides pre-sale compatibility checks and post-sale technical assistance for integration
- Warranty & Traceability: All units supplied with inspection report, serial number traceability, and minimum 12-month warranty
Typical Applications
- Automotive Manufacturing: Legacy assembly line control panels requiring PLC-2 processor continuity
- Food & Beverage Processing: Conveyor and packaging line controllers with existing 1772 I/O infrastructure
- Water Treatment Plants: Pump station and valve sequencing systems on PLC-2 platforms
- Chemical Processing: Batch control systems where program re-validation costs prohibit platform migration
- Material Handling: Warehouse conveyor and sortation systems with installed 1772 chassis
- Power Generation & Utilities: Auxiliary control panels in substations and generation facilities running legacy PLC-2 logic
System Compatibility
The 1772-LS operates within the following Allen-Bradley PLC-2 ecosystem components:
- 1772-A1 / A2 / A3 / A4 — PLC-2 I/O chassis (4, 8, 12, 16 slot)
- 1772-P1 / P2 / P3 — PLC-2 power supply modules
- 1771-OA / OB / OD — Compatible discrete output modules
- 1771-IA / IB / ID — Compatible discrete input modules
- 1772-T3 — PLC-2 programming terminal interface
- 1784-KT / 1784-KTX — Data Highway communication interface cards
- APS / 6200 Series Software — Programming and monitoring software
Selection Guide
Answer these three questions to confirm the right module for your application:
- Is your existing chassis a 1772-A series? If yes, the 1772-LS or 1772-LSP is a direct drop-in. If no, contact Konmask to assess adapter requirements.
- Does your application require the existing PLC-2 program to run without modification? If yes, only OEM 1772-LS or 1772-LSP units qualify. If program conversion is acceptable, functional equivalents or migration platforms may reduce cost.
- What is your I/O point count and memory requirement? If >128 I/O or >1K words, the 1772-LS is insufficient — consider 1772-LX or 1772-LXP equivalents.
📩 Not sure which model fits? Contact Konmask at support@konmask.com — our engineers respond within 24 hours with a compatibility assessment.
Quality Assurance & Sourcing
Sourcing Channels: Konmask sources 1772-LS units from authorized surplus distributors, OEM-certified refurbishers, and factory-sealed new-old-stock (NOS) inventory with full chain-of-custody documentation.
4-Step Inspection Process:
- Visual Inspection: Board-level examination for corrosion, component damage, and counterfeit indicators
- Functional Test: Power-on test in a live 1772 chassis with I/O simulation to verify processor operation
- Firmware Verification: Revision level confirmed and documented against OEM specifications
- Final QC & Packaging: ESD-safe packaging, serial number logging, and inspection report generation
Available Documentation: Certificate of conformance, inspection report, test data sheet, and country-of-origin declaration available upon request.
How to Order
- Submit Your Inquiry: Email support@konmask.com with part number (1772-LS), required quantity, and any firmware or revision requirements
- Receive Quotation & Compatibility Confirmation: Konmask engineering team reviews your application and responds with pricing, lead time, and compatibility notes within 24 hours
- Confirm & Ship: Upon order confirmation, units are inspected, documented, and dispatched with full traceability paperwork
Replacement & Compatibility FAQ
Q: Can I replace a 1772-LS with a 1772-LSP without modifying my program?
A: Yes, the 1772-LSP is a functional equivalent and direct substitute for the 1772-LS in the same chassis. Your existing PLC-2 program can be re-uploaded without modification. Verify the firmware revision is compatible with your programming software version.
Q: Is the Allen-Bradley MicroLogix 1100 compatible with the 1772-LS chassis?
A: No. The MicroLogix 1100 is not a drop-in replacement for the 1772-LS. It uses a different form factor, I/O bus, and instruction set. It is a migration alternative requiring new chassis, I/O modules, and program conversion from PLC-2 to RSLogix 500 format.
Q: Where can I find a genuine 1772-LS equivalent with warranty?
A: Konmask supplies inspected, tested 1772-LS units and functional equivalents (1772-LSP, 1772-LX) with a minimum 12-month warranty and full traceability documentation. Contact support@konmask.com or call +0086 19859288691 for availability and pricing.
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