Allen-Bradley 1771-A4B 16-Slot I/O Chassis | Replacement, Equivalent & Selection Guide
The Allen-Bradley 1771-A4B is a 16-slot I/O chassis designed for use with Rockwell Automation PLC-5 programmable controller systems. It provides a robust, modular backplane for housing I/O modules, communication adapters, and specialty modules in industrial automation environments. This page serves as a comprehensive selection and replacement reference for engineers, maintenance teams, and procurement specialists.
Technical Specifications
- Part Number: 1771-A4B
- Manufacturer: Allen-Bradley / Rockwell Automation
- Series: PLC-5 I/O Chassis
- Number of Slots: 16
- Backplane Type: 1771 I/O Backplane
- Power Supply Compatibility: 1771-P4S, 1771-P6S, 1771-P7 series
- Module Compatibility: All 1771 series I/O and specialty modules
- Mounting: Panel or rack mount
- Weight: Approx. 6.24 kg
- HS Code: 853710
- Condition Available: New, Surplus New, Refurbished
Compatible Replacement & Equivalent Models
If the 1771-A4B is discontinued, hard to source, or outside budget, the following models offer compatible or equivalent functionality:
- 1771-A4B/E – Enhanced revision of the same chassis; direct drop-in replacement
- 1771-A3B – 12-slot variant; suitable when fewer I/O slots are required
- 1771-A2B – 8-slot variant; compact alternative for smaller I/O counts
- 1771-A1B – 4-slot variant; minimal footprint option
- 1756-A17 (ControlLogix) – Modern 17-slot chassis; requires migration to ControlLogix platform
- 1756-A13 (ControlLogix) – 13-slot ControlLogix chassis; migration path for legacy PLC-5 systems
Note: ControlLogix replacements require re-engineering of the control program and I/O wiring. Consult your system integrator before migrating.
Why Choose the Original 1771-A4B
- Proven Reliability: Decades of field-proven performance in demanding industrial environments
- Maximum Slot Density: 16 slots accommodate large I/O counts without additional chassis
- Full 1771 Module Compatibility: Supports the complete range of 1771 analog, digital, and specialty modules
- Minimal Downtime Risk: Direct replacement with no software or wiring changes required
- Cost-Effective Maintenance: Extending PLC-5 system life avoids costly platform migrations
Typical Applications
- Automotive assembly line control systems
- Oil & gas process automation and SCADA integration
- Water and wastewater treatment plant control
- Food and beverage packaging line automation
- Power generation and distribution control panels
- Legacy PLC-5 system maintenance and spare parts management
System Compatibility
The 1771-A4B chassis is compatible with the following Allen-Bradley / Rockwell Automation system components:
- Controllers: PLC-5/10, PLC-5/15, PLC-5/20, PLC-5/30, PLC-5/40, PLC-5/60, PLC-5/80
- Power Supplies: 1771-P4S, 1771-P6S, 1771-P7
- I/O Modules: All 1771 series digital, analog, and specialty modules
- Communication Adapters: 1771-ASB, 1771-DCM, 1771-KA series
- Programming Software: RSLogix 5, 6200 Series Programming Software
Selection Guide
Use the following criteria to select the correct chassis for your application:
- I/O Count: Count total required I/O points. Each slot holds one module (typically 8–32 I/O points). Choose 1771-A4B (16 slots) for high-density applications.
- Power Budget: Verify total module current draw does not exceed the selected power supply rating (e.g., 1771-P4S = 4A @ 5VDC backplane).
- Expansion Needs: For systems requiring >16 slots, use multiple chassis connected via 1771-ASB remote I/O adapter.
- Environment: Standard industrial environment. For hazardous locations, verify module-level certifications.
- Migration vs. Maintenance: If PLC-5 EOL is a concern, evaluate ControlLogix migration. For short-to-medium term continuity, source original 1771-A4B.
Quality Assurance & Sourcing
- All units sourced from authorized distributors or verified surplus channels
- Pre-shipment functional inspection and visual quality check
- Original manufacturer packaging preserved where available
- Traceability documentation available upon request
- Warranty: 90-day replacement warranty on all stocked units
- Anti-counterfeit verification process applied to all Allen-Bradley products
How to Order
- Confirm part number: 1771-A4B (specify revision if required, e.g., /E)
- Specify required condition: New / Surplus New / Refurbished
- Provide quantity and required delivery timeline
- Contact us via email or phone for a formal quotation
- Purchase orders accepted from verified industrial buyers and system integrators
📧 support@konmask.com | 📞 +0086 19859288691
Replacement & Compatibility FAQ
Q: Is the 1771-A4B still in production?
A: The 1771 series has reached end-of-life (EOL) status with Rockwell Automation. However, surplus new and refurbished units remain available through authorized aftermarket suppliers like Konmask.
Q: Can I use a 1771-A4B/E in place of a 1771-A4B?
A: Yes. The /E revision is a direct functional replacement with minor hardware revisions. No software or wiring changes are required.
Q: What is the difference between 1771-A4B and 1771-A3B?
A: The 1771-A4B has 16 slots; the 1771-A3B has 12 slots. Both use the same 1771 backplane standard and are compatible with the same modules and power supplies.
Q: Can I replace a PLC-5 system with ControlLogix using this chassis?
A: No. ControlLogix uses the 1756 chassis family. Migration from PLC-5 to ControlLogix requires new hardware, re-engineering of the control program, and I/O rewiring.
Q: Do you provide datasheets or technical documentation?
A: Yes. Contact us at support@konmask.com to request the official Allen-Bradley 1771-A4B installation instructions and technical specifications.
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Contact: support@konmask.com | +0086 19859288691
