PRODUCT INFORMATION
Product Overview
The Allen-Bradley 1771-ALX is an extended local I/O adapter module for PLC-5 control systems. This module expands system input and output capacity across remote chassis locations. It allows physical chassis disconnection without interrupting backplane operation on other racks. The module installs directly into the leftmost slot of any 1771 chassis. It works with Series A and Series B 1771 backplanes without hardware modifications. It draws 1.2 Amperes of backplane current at 5 Volts DC.
This local I/O adapter connects to processor chassis using dedicated parallel interconnect cables. Supported interconnect assemblies include 1771-CX1, 1771-CX2, and 1771-CX5 cables. Total allowable cable distance extends up to 30 meters or 98.4 feet. A 1771-CXT terminator plug must terminate the final chassis on the expansion bus. Three diagnostic status LEDs indicate operating health, adapter faults, and rack fault conditions. The module operates in ambient temperatures ranging from 0 to 60 degrees Celsius.
TECHNICAL DATA
Technical Specifications
| Parameter | Specification |
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| Category | PLCs |
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| UPC | 612598115372 |
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| Weight | 1.88 lbs (0.85 kg) |
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| Module Type | Local I/O adapter |
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| Max Backplane Current (at 5 Volts DC) | 1.2 A |
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| Module location | Leftmost slot in any 1771 I/O chassis |
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| Installation slot | Left most slot |
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| Interconnect cable | 1771-CX1 (1 meter); 1771-CX2 (2 meters); 1771-CX5 (5 meters) |
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| Cable terminator | 1771-CXT |
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| Keying | Between 54 and 56; Between 4 and 6 |
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| Chassis distance | 30 cable-meters (98.4 cable-feet) |
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| Compatibility | Series A or B 1771 IO chassis |
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| Power supply | 1771 external or slot power supplies |
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| LED indicators | ACTIVE: ADAPTER FAULT; I/O RACK Fault |
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| Rack Addressing | Any method |
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| Port | Extended Local I/O Adaptor |
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| Connectors | D-Shell |
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| Compatible chassis | Series A or B 1771 I/O |
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| Backplane Current (at 5 Volts) | 1.2 Amperes |
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| Compatible Power supply | 1771 external or slot power supplies |
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| Cable | 1771-CX1 (1 m), 1771-CX2 (2 m), 1771-CX5 (5 m) |
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| Backplane Current at 5.1 Volts | 1.2 A |
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| Operating Temperature | 32-140 F (0-60 C) |
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| Storage Temperature | -40-185 F (-40-85 C) |
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| Lower Connector Keying | 16-18 |
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| Power Dissipation | 6.3 Watts (max.); 5.7 Watts (min.) |
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| Thermal Dissipation | 21.48 BTU/hr (max.); 19.44 BTU/hr (min.) |
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| Operational Temperature | 0 to 60 oC (32 to 140 oF) |
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| Relative Humidity | 5 to 95% (without condensation) |
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TECHNICAL INFORMATION
Features
- Connects local 1771 I/O chassis to PLC-5 programmable controllers over parallel communication cables.
- Supports total interconnect cable lengths up to 30 meters or 98.4 feet.
- Installs in the leftmost slot of any Series A or Series B 1771 chassis.
- Permits safe chassis disconnection from the bus without shutting down the entire system.
- Features three front status LEDs for active status, adapter fault, and rack fault monitoring.
- Requires a 1771-CXT bus termination plug at the final chassis location.
TECHNICAL INFORMATION
Applications
- Local I/O chassis expansion across multi-rack Allen-Bradley PLC-5 control architectures.
- Distributed machine automation panels requiring modular physical separation within 30 meters of the controller.
- Maintenance retrofits requiring chassis isolation without interrupting primary backplane communication.
TECHNICAL INFORMATION
Connections / Interfaces
- D-shell port designed for 1771-CX series parallel expansion cables.
- Compatible with 1771-CX1 one-meter, 1771-CX2 two-meter, and 1771-CX5 five-meter cable assemblies.
- Requires a 1771-CXT terminator plug installed at the end of the expansion run.
TECHNICAL INFORMATION
Installation Guidelines
- Remove power to the backplane before inserting or removing the module.
- Mount the module exclusively in the leftmost slot of the 1771 chassis.
- Verify keying bands between pins 54 and 56 and between pins 4 and 6.
- Observe lower connector keying positions 16 through 18 prior to full seating.
- Limit overall cable runs to 30 meters across all interconnected expansion chassis.
TECHNICAL INFORMATION
Configuration Guidelines
- Supports all standard PLC-5 rack addressing modes without module restrictions.
- Ensure the final adapter chassis on the cable line has a 1771-CXT terminator installed.
TECHNICAL INFORMATION
Compatibility
- Compatible with Allen-Bradley Series A and Series B 1771 I/O chassis.
- Compatible with all 1771 external power supplies and slot power supplies.
- Operates in Allen-Bradley PLC-5 programmable controller architectures.
TECHNICAL INFORMATION
Lifecycle / Replacement Information
- The 1771-ALX module belongs to legacy Allen-Bradley PLC-5 product families.
- Replacement units are typically sourced through surplus, remanufactured, or refurbished distribution channels.
TECHNICAL RESOURCES
Documentation
COMPATIBILITY
Compatibility & Replacement
COMPATIBLE MODELSCompatible with Allen-Bradley Series A and Series B 1771 I/O chassis. Compatible with all 1771 external power supplies and slot power supplies. Operates in Allen-Bradley PLC-5 programmable controller architectures.
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
What is the function of the Allen-Bradley 1771-ALX module?
The 1771-ALX extends local I/O communication between a PLC-5 controller and remote 1771 chassis.
Which chassis slot does the 1771-ALX require?
The module must always be installed in the leftmost slot of a 1771 I/O chassis.
What cables connect the 1771-ALX adapter?
It uses 1771-CX1, 1771-CX2, and 1771-CX5 cables with a maximum total distance of 30 meters.
Does the 1771-ALX require a bus terminator?
Yes. A catalog number 1771-CXT terminator plug must be installed at the last chassis on the expansion line.
What is the indicative market reference price for the 1771-ALX?
Observed market reference pricing is around 109.00 USD. This figure is an indicative market reference only and not a final quotation.
