The Allen Bradley 1771-A1B is a 4-slot PLC-5 I/O chassis (rack assembly) used in Allen-Bradley 1771 series control systems. It serves as the physical backplane that holds I/O modules, power supplies, and communication adapters, enabling data exchange between field devices and the PLC processor.
This chassis is part of the legacy PLC-5 architecture and is still found in many long-life industrial installations such as manufacturing plants, utilities, and process control systems.
Technical Specifications (Mechanical & Electrical)
| Parameter | Specification |
|---|---|
| Manufacturer | Allen Bradley (Rockwell Automation) |
| Catalog Number | 1771-A1B |
| Product Type | I/O Chassis / Rack Assembly |
| Series | PLC-5 / 1771 I/O |
| Number of Slots | 4 slots |
| Backplane Voltage | 5.25 V DC |
| Backplane Current Capacity | Up to 16 A |
| Supported Modules | I/O modules, CPU, adapter, power supply |
| Compatible Power Supplies | 1771-P1, 1771-P2, 1771-P7, 1771-PS7 |
| Mounting Type | Panel mount |
| Enclosure Type | Open-style chassis |
| Operating Temperature | 0°C to 60°C |
| Storage Temperature | -40°C to 85°C |
| Dimensions | Approx. 89 × 165 × 51 mm |
| Weight | Approx. 3.6 kg |
System Architecture Role
The 1771-A1B functions as the central backplane structure in PLC-5 systems. It provides electrical connection and communication pathways between installed modules.
Key system roles include:
- Housing PLC-5 processor or I/O adapter module
- Providing backplane communication bus
- Distributing power to I/O modules
- Supporting remote and local I/O configurations
- Acting as the physical backbone of PLC-5 control architecture
Recommended Related Components
| Model | Function |
|---|---|
| 1771-P7 | Chassis Power Supply |
| 1771-ASB | Remote I/O Adapter Module |
| 1771-IBD | Digital Input Module |
| 1771-OBD | Digital Output Module |
| 1771-IFE | Analog Input Module |
| 1771-OWNA | Relay Output Module |
Common Allen Bradley Legacy PLC Hardware
| Model | Role |
|---|---|
| 1771-A2B | 8-slot I/O chassis |
| 1771-A3B | 12-slot I/O chassis |
| 1771-A4B | 16-slot I/O chassis |
| 1785-L40B | PLC-5 Processor |
| 1771-SN | I/O Scanner Module |
| 1771-DH | Data Highway Communication Module |
