PRODUCT INFORMATION
Product Overview
The Allen-Bradley 1771-A4B is a 16-slot I/O chassis designed for the PLC-5 control system architecture. This modular chassis assembly provides structural backplane interconnects for system hardware. The chassis manages up to four logical I/O racks when using 1/2-slot addressing. Its leftmost backplane slot accepts either a processor module or an I/O adapter module.
Communication modules and standard I/O modules install into any backplane slot except the leftmost slot. Power supply modules rated from 3 to 8 amperes also mount in non-leftmost slots. The backplane works with processors having integral power supplies rated between 2 and 4 amperes. External power supplies rated from 6.5 to 16 amperes can also power the chassis.
TECHNICAL DATA
Technical Specifications
| Parameter | Specification |
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| UPC | 612598123483 |
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| Weight | 20.31 lbs (9.21 kg) |
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| Max. Number of Assigned I/O Racks | 4 I/O Racks with 1/2-Slot Addressing |
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| Required Number of Plastic Keying Bands | 36 keying bands required for installation |
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| Required Washers for Installation | One cup washer, one star washer, four flat washers, and two #10 to 32 nuts with captive lock washers |
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| Mounting Option | Panel mounting (rear mounting) |
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| Grounding | Supported |
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| Compatible Processors that Have Integral Power Supplies | Processors rated at 2 to 4 Amps |
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| Compatible Power Supply Modules | Modules rated at 3 to 8 Amps |
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| Compatible External Power Supplies | Power supplies rated at 6.5 to 16 Amps |
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| Processor Module Installation | Supported in leftmost slot |
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| I/O Adapter Module Installation | Supported in leftmost slot |
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| Communication Module Installation | Supported in all slots except the leftmost slot |
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| I/O Module Installation | Supported in all slots except the leftmost slot |
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| Power Supply Module Installation | Supported in all slots except the leftmost slot |
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| Number of I/O Module Slots | 16 Slots |
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TECHNICAL INFORMATION
Features
- Provides 16 backplane module slots for modular PLC-5 hardware.
- Manages up to 4 logical I/O racks using 1/2-slot addressing.
- Features a dedicated leftmost slot for processor or adapter modules.
- Accepts chassis power supply modules rated from 3 to 8 amperes.
- Connects to compatible external power supplies rated from 6.5 to 16 amperes.
- Supports rear panel mounting inside standard industrial enclosures.
TECHNICAL INFORMATION
Applications
- Centralized PLC-5 processor installations using local chassis architecture.
- Remote I/O station configurations using a 1771 I/O adapter module.
TECHNICAL INFORMATION
Connections / Interfaces
- Dedicated leftmost backplane connector for a processor or I/O adapter module.
- Fifteen standard backplane slots for communication, power, and I/O modules.
- Integrated grounding connection to support plant equipment safety bonding.
TECHNICAL INFORMATION
Installation Guidelines
- Secure the chassis assembly using rear panel mounting orientation.
- Insert 36 plastic keying bands to prevent improper module alignment.
- Install one cup washer, one star washer, and four flat washers.
- Tighten two number 10-32 nuts with captive lock washers for secure attachment.
- Bond the chassis grounding connection directly to plant earth ground.
TECHNICAL INFORMATION
Configuration Guidelines
- Configure the chassis backplane for 1/2-slot addressing to manage up to four racks.
- Reserve the leftmost chassis slot exclusively for processor or adapter hardware.
- Ensure power supply ratings match total backplane module load requirements.
TECHNICAL INFORMATION
Compatibility
- Accepts PLC-5 processor modules exclusively in the leftmost backplane slot.
- Accepts 1771 I/O adapter modules exclusively in the leftmost backplane slot.
- Accommodates standard 1771 I/O modules in all slots except the leftmost position.
- Supports compatible internal power supply modules rated from 3 to 8 amperes.
- Operates with external power supplies rated between 6.5 and 16 amperes.
TECHNICAL RESOURCES
Documentation
COMPATIBILITY
Compatibility & Replacement
COMPATIBLE MODELSAccepts PLC-5 processor modules exclusively in the leftmost backplane slot. Accepts 1771 I/O adapter modules exclusively in the leftmost backplane slot. Accommodates standard 1771 I/O modules in all slots except the leftmost position. Supports compatible internal power supply modules rated from 3 to 8 amperes. Operates with external power supplies rated between 6.5 and 16 amperes.
Verify compatibility against the exact Part Number, revision and manufacturer documentation before ordering.
PART VERIFICATION
Before You Order
Industrial automation parts can share similar model names, suffixes and revisions. Confirm the complete manufacturer Part Number before purchase.
01Check Part NumberMatch the complete ordering code on the existing unit.
02Confirm RevisionCheck suffix, hardware or firmware when applicable.
03Send a Label PhotoWe can review a clear label photo when identification is uncertain.
ORDERING PROCESS
From RFQ to Dispatch
1Submit Part Number2Verify Product Identity3Confirm Stock & Condition4Issue Quotation5Dispatch & Tracking
PRODUCT FAQ
Frequently Asked Questions
Which modules fit into the leftmost slot of the 1771-A4B chassis?
The leftmost slot accommodates only a PLC-5 processor module or an I/O adapter module.
What power supplies are compatible with the 1771-A4B backplane?
The chassis supports internal power modules rated 3 to 8 amperes and external supplies rated 6.5 to 16 amperes.
What mounting hardware is needed to install the 1771-A4B?
Installation requires one cup washer, one star washer, four flat washers, and two number 10-32 nuts with lock washers.
What is the reference price for an Allen-Bradley 1771-A4B chassis?
Observed market reference pricing is 199.00 USD. This figure represents indicative reference pricing only and not a final quotation.
