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        • Lifecycle status

          Discontinued / Obsolete by OEM
          Apter Power supplies fully verified Allen-Bradley 1771-OB output modules, giving maintenance professionals an immediate and trusted source for essential automation spares.

        1771-OB

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        1001 reviews ｜ Need a Specific Revision?
        The Allen Bradley 1771-OB is a 8-point DC output module engineered for the PLC-5 and 1771 I/O platform, designed to deliver reliable switching control for demanding industrial automation environments.
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        Ships by Thursday, October 29
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        Warranty Policy
        We provide 1 year warranty for all remaining parts.
        The warranty period is one year from the date of shipment, unless otherwise stated in the parts description. We guarantee that the project will not exhibit functional defects that may occur under normal operating conditions during the warranty period.
        Return Notice
        The warranty period is one year from the date of shipment, unless otherwise stated in the parts description. We guarantee that the project will not exhibit functional defects that may occur under normal operating conditions during the warranty period.
        In the event of a defect, we will send new equipment, repair equipment or refund the purchase price based on our availability. You must contact us to obtain a return authorization and return the defective device to us within 14 days of reporting the defect.
        Shipping Mode
        Various transportation options are available in each country. Shipping methods and fees are clearly indicated on all quotations.Various transportation options are available in each country. Shipping methods and fees are clearly indicated on all quotations.
        Parts Availability
        Apter Power offers a wide range of components, products and services related to industrial automation. We also supply new products from a variety of quality manufacturers.
        How to order
        We have been working hard to update our inventory. If we have stock or parts available for new factory purchases, you can contact the order online. If we do not currently have an inventory, the displayed quantity will show "Ask". Please create an online quote or contact us by phone, fax or email to check availability.

        Technical specifications for 1771-OB

        • Manufacturer:
          Allen-Bradley
        • Part Number:
          1771-OB
        • Product Family:
          PLC-5
        • Product Type:
          DC Output Module
        • Stock:
          1
        • Number of Outputs:
          8 points (Non-isolated channel-to-channel, Sourcing)
        • Output Voltage Range:
          10 to 27V DC
        • Output Current Rating:
          1.5A maximum per output, 8A maximum per module
        • Surge Current Capacity:
          4A maximum per output for 1 ms (Repeatable every 1 second)
        • Off-State Leakage Current:
          1 mA maximum per output at 27V DC (25°C)
        • On-State Voltage Drop:
          2V DC maximum
        • Output Signal Delay:
          10 ms maximum for both ON and OFF transitions
        • Backplane Power Demand:
          165 mA at 5V DC (±5%)
        • Power Dissipation:
          16.9 Watts maximum, 0.9 Watts minimum
        • Thermal Dissipation:
          57.6 BTU/hr maximum, 3.0 BTU/hr minimum
        • Operating Temperature:
          0°C to 60°C (32°F to 140°F)
        • Storage Temperature:
          -40°C to 85°C (-40°F to 185°F)
        • Weight:
          0.6 kg
        • Estimated shipping dimensions:
          3x15.2x26cm
        • Tariff Code:
          8537101101
        • Country of origin:
          USA
        • Place of shipment:
          Xiamen, Fujian, China
        By purchasing this item, you agree to the Terms & Conditions, ApterPower is not an authorized distributor for listed manufacturers or tradenames and therefore the manufacturer's warranty does not apply. All our products come with ApterPower's 1-year warranty.

        More Information

        Overview Manuals Specifications Applications Monitoring & Control Safety & Compliance

        Features:

        • Integrated Diagnostic Fusing for Enhanced Uptime
        • Robust Load-Handling Capacity in Compact Form
        • Reliable Modular Integration and Safety Keying
        The Allen Bradley 1771-OB features individual 2A 8AG fuses for each of its eight output channels, supported by a central blown-fuse indicator. This direct diagnostic capability allows maintenance personnel to instantly pinpoint short circuits or overloads at the channel level, minimizing diagnostic complexity and significantly reducing plant downtime during critical operational cycles.

        Engineered to drive demanding field loads up to 1.5A per point with a total module capacity of 8A, the Allen Bradley 1771-OB handles high-surge inductive loads like motor starters and solenoids effortlessly. Its built-in surge handling capability (up to 4A for 1ms) ensures stable switching performance without premature component degradation in harsh industrial electrical environments.

        The Allen Bradley 1771-OB incorporates precise mechanical keying features (between positions 4-6 and 18-20) to prevent incorrect module insertion into the 1771 I/O chassis. Combined with the 1771-WA field wiring arm, it secures field wiring integrity, allowing swift module replacement or servicing without disturbing complex panel-level wiring configurations.

        The 1771-OB Allen Bradley DC Output Module may still be available for purchase and support from Apter Power beyond End-Of-Life (EOL) by the manufacturer (OEM).
        Allen Bradley 1771-OB DC Output Module Manuals,Datasheets,Link Important Notice: Other accessories, manuals, cables, calibration data, software, etc. are not included with this equipment unless listed in the above stock item description. All prices are shown in USD.
        Allen Bradley 1771-OB DC Output Module

        General

        • Manufacturer Allen Bradley
        • Model 1771-OB
        • Condition New Original ready stock
        • Product Family 1771-OBD,1771-OZL,1771-OM
        Important Notice: Other accessories, manuals, cables, calibration data, software, etc. are not included with this equipment unless listed in the above stock item description. All prices are shown in USD.
        • Discrete Assembly Line Driving: The Allen Bradley 1771-OB excels in automotive body shops and general assembly plants, safely commanding high-cycle DC pilot valves, automated clamping solenoids, and physical line-status signaling fixtures.
        • Process Valve and Actuator Distribution: It acts as a dependable control interface within chemical or water treatment process skid matrices, distributing discrete DC signals to drive chemical dosing valves, auxiliary relays, and safety beacons.
        • Legacy Control Lifecycle Extensions: For industrial facilities running critical PLC-5 processing cells, the module serves as a direct drop-in replacement component, keeping older production cells running productively without requiring a complete control system redesign.
        • Material Handling and Sorting Systems: This digital output module manages high-frequency sorting mechanisms, conveyor diverters, and localized DC contactor coils within large logistics distribution centers and baggage handling zones.
        • Instantaneous Front-Panel Diagnostics: The dual-purpose diagnostic LED array lets field electricians check both active channel command states and open-fuse states on the fly, entirely cutting out the need to open up hot electrical enclosures with multimeters.
        • Predictable Deterministic Timing: Offering a stable 10 ms maximum signal propagation delay for both rising and falling edges, it gives automated machinery highly consistent, repeatable step execution within tightly timed control loop routines.
        • Stable Current Load Management: The solid-state design easily regulates up to 1.5A per channel continuously, offering robust power distribution to inductive loads while safely managing heat via a heavy-duty chassis design.
        • Direct Backplane Memory Mapping: Because it links directly into the 1771 Universal I/O chassis memory layout, it provides high-speed, cyclic data updating to the central CPU, ensuring highly reliable command delivery.
        • Hazardous Environment Suitability: Thanks to its certified CSA Class I Division 2 rating, the module is fully approved for volatile process plants where flammable vapors or gases might occasionally accumulate in the atmosphere.
        • Robust Opto-Electrical Isolation: Built with a 1500V AC RMS isolation barrier between the field-side wiring and the backplane logic, it creates an electrical firewall that stops field-induced voltage surges from knocking out expensive central processors.
        • Global Regulatory Endorsements: Compliance with stringent UL, CSA, and CE directives guarantees that machinery builders can integrate this component into equipment packages destinado for international export with zero regulatory resistance.
        • Channel-Level Risk Mitigation: Incorporating individual 2A fuses on every single output channel ensures that an electrical short on a single field solenoid is instantly isolated, keeping the other seven healthy channels operating normally.
        Description
        The Allen Bradley 1771-OB stands as a premier solution within Rockwell Automation’s legacy catalog, purposely built to handle demanding digital on/off operations. It provides high-utility switching control for a vast range of field devices, including heavy-duty industrial DC solenoids, pilot lights, indicators, and motor starters. Operating safely within a wide 10 to 27V DC voltage range, this solid-state module delivers an exceptionally long operational lifespan that minimizes total cost of ownership (TCO) for plants running continuous operations.

        Designed with critical maintenance pain points in mind, the module incorporates a per-point diagnostic architecture to minimize Mean Time to Repair (MTTR). Each of the eight sourcing output points is backed by its own dedicated 2A 8AG protective fuse. Coupled with a front-panel blown-fuse indicator, maintenance teams can instantly spot, isolate, and remediate localized overloads or short circuits without triggering unmanaged cascading electrical system failures or extensive troubleshooting.

        From an integration standpoint, the Allen Bradley 1771-OB installs effortlessly inside standard 1771 Universal I/O chassis and utilizes the time-tested 1771-WA field wiring arm. System engineers can leverage physical plastic keying bands to bind chassis slots specifically to this module type, making field replacements foolproof for junior instrumentation technicians. This prevents hazardous module mismatches, simplifies plant floor maintenance, and maximizes overall system runtime.
        Revisions

        Revision Part #

        Also known as

        1771-OB Ser A
        1771-OB/A, Series A, Rev A
        Get Parts Quote
        1771-OB Ser B
        1771-OB/B, Series B, Rev B
        Get Parts Quote
        1771-OB Ser C
        1771-OB/C, Series C, Rev C
        Get Parts Quote
        Alternative Names
        1771OB I77I-OB 1771-0B 1771-O8 1771-08 1771-OBD 1771-OZL 1771-OM
        Technical notes
        The Allen Bradley 1771-OB requires a compatible 1771 Universal I/O chassis and a 1771-WA field wiring arm, drawing a stable 165 mA from the backplane power supply at 5V DC. To guarantee absolute field safety and prevent high-voltage mismatching, it is highly recommended to configure the chassis mechanical slot keying specifically between pins 4 to 6 and pins 18 to 20 during initial hardware installation.
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        FAQS

        The following is a list of questions commonly asked by our customers. Please contact us if you have a question about our process that is not answered below.
        VIEW ALL FAQS
        What is the backplane current draw required by the Allen Bradley 1771-OB, and how does it impact system power budgeting?
        The Allen Bradley 1771-OB draws a maximum of 165 mA at 5V DC from the chassis backplane. System integrators must aggregate this value alongside all other modules in the local rack to ensure total current draw stays safely within the rated capacity of the associated 1771 power supply, preventing under-voltage drops or backplane instability.
        How does the Allen Bradley 1771-OB handle inductive load switching transients?
        The Allen Bradley 1771-OB accommodates surge currents up to 4A per output for 1 millisecond (repeatable every second). However, when controlling highly inductive devices (e.g., relays or solenoids) that sit in series or parallel with a "hard contact" switch like a pushbutton, it is highly recommended to add an external suppression device (snubber) directly across the inductive coil to protect field switch contacts and prevent output transistor wear.
        What firmware or software environment is required to configure and monitor the Allen Bradley 1771-OB?
        The Allen Bradley 1771-OB maps directly into the standard I/O output image table of the host processor, utilizing 8 bits of data. It functions natively across all classic programmable controllers without requiring complex custom firmware flashing, modern parameterization profiles, or software-defined I/O configuration steps.
        Can the Allen Bradley 1771-OB be used alongside digital input modules in the same backplane zone?
        Yes. The Allen Bradley 1771-OB can be deployed alongside discrete input modules like the 1771-IB in the same chassis. To minimize ground loop interference and maintain tight local loop control, engineers can safely power both the output module and the corresponding input module from a single, shared DC power source, ensuring a uniform ground reference.
        What diagnostic feedback does the Allen Bradley 1771-OB provide regarding field-side faults?
        The front panel of the Allen Bradley 1771-OB features nine red status indicators. The top LED acts as a global fuse-blown alert that illuminates instantly when a protective circuit opens. The remaining eight LEDs provide clear, real-time visual diagnostics by lighting up only when a true voltage state is actively present on that specific field terminal.

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