1756-OB8 | Allen-Bradley ControlLogix 8-Point 24VDC Digital Output Module
1756-OB8 | Allen-Bradley ControlLogix 8-Point 24VDC Digital Output Module
1756-OB8 | Allen-Bradley ControlLogix 8-Point 24VDC Digital Output Module
    1756-OB8 | Allen-Bradley ControlLogix 8-Point 24VDC Digital Output Module
1756-OB8 | Allen-Bradley ControlLogix 8-Point 24VDC Digital Output Module

1756-OB8 | Allen-Bradley ControlLogix 8-Point 24VDC Digital Output Module

Part #: 1756-OB8 Manufactured by: Allen-Bradley
$482.00
$482.00
3 in Stock
Condition: New – Open box
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Product Overview
Allen Bradley ControlLogix DC Output Module with 8-Point Outputs
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Product Description P/N: 1756-OB8

Description / Specifications

Description 

The Allen-Bradley 1756-OB8 is an 8-point 24VDC digital output module for ControlLogix chassis, providing sourcing outputs in two isolated groups. Each channel operates within a 10–30VDC range with a nominal 24VDC signal level and supports up to 2 A per point. The module connects through the 1756-TBNH or 1756-TBSH removable terminal blocks and integrates into both local and distributed ControlLogix I/O systems.

 

 

Technical Specifications 

Condition New/Never Used Surplus
Brand Allen-Bradley
Category I/O Modules
Part Number 1756-OB8
Subcategory Digital Output Modules
Series ControlLogix
Module Type 24VDC Sourcing Output Module
Number of Outputs 8
Output Groups 2 groups of 4
Output Voltage Range 10–30VDC
Nominal Output Voltage 24VDC
Max Current per Point 2 A @ 60°C
Max Current per Module 8 A @ 60°C
Backplane Current (5.1V) 165 mA
Backplane Current (24V) 2 mA
Backplane Power 0.89 W
Power Dissipation 2.5 W @ 60°C
Isolation Voltage 50V continuous
Removable Terminal Blocks 1756-TBNH, 1756-TBSH
ON Signal Delay ≤1 ms
OFF Signal Delay ≤2 ms
Surge Current 4 A for 10 ms (1 s repeat)
Minimum Load Current 2 mA
Operating Temperature 0–60°C
Storage Temperature –40 to 85°C
Humidity 5–95% non-condensing
Enclosure None (requires ControlLogix chassis)

  

 

Information About 1756-OB8

The 1756-OB8 is part of the ControlLogix platform, offering a modular digital output solution with eight DC sourcing channels arranged in two groups of four. Its design incorporates solid-state output circuitry with configurable behavior in program and fault modes, enabling flexible operation in automation systems. The module is compatible with all standard ControlLogix chassis and supports rack-optimized, scheduled, and listen-only communication formats. Typical applications include controlling DC loads such as solenoids, relays, pilot devices, and interposing circuits within industrial control architectures requiring robust 24VDC output performance.

Key Features:

  • 8 sourcing outputs: Provides eight 24VDC output channels in two groups.
  • 10–30VDC operating range: Nominal 24VDC signal supports most industrial devices.
  • 2 A per point at 60°C: Suitable for medium-duty DC load control.
  • 8 A per module maximum: Supports aggregated current demands across channels.
  • Fast switching times: 1 ms ON and 2 ms OFF typical signal delay.
  • Compatible RTBs: Works with 1756-TBNH and 1756-TBSH removable terminal blocks.
  • ControlLogix backplane integration: Supports multiple communication formats including rack optimization.
  • Configurable fault and program states: Per-point selection of Hold Last State, ON, or OFF.
  • Continuous isolation voltage: Rated at 50V for noise and signal protection.
  • Minimal power consumption: Draws 165 mA at 5.1VDC and 2 mA at 24VDC from the backplane.
  • Wide environmental tolerances: Operates from 0–60°C with 5–95% non-condensing humidity.

The 1756-OB8 delivers the reliability and precision required for dependable digital output control in ControlLogix automation systems.

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Frequently Asked Questions about 1756-OB8
Question: What is the 1756-OB8 used for?
Date Update:20/06/2025
Answer:

The 1756-OB8 is an 8-point DC digital output module designed for ControlLogix systems. Its main purpose is to switch external DC loads such as relays, solenoids, and indicators by sourcing current from each output channel. It delivers 24VDC nominal output across a voltage range of 10–30VDC. Each channel can handle up to 2 A of output current, while the total module current is limited to 8 A at 60°C. The module can be configured in distributed or local I/O systems and supports various output data modes. This makes it ideal for precise and reliable control in industrial automation applications.

Question: Is 1756-OB8 hot-swappable?
Date Update:20/06/2025
Answer:

Yes, the 1756-OB8 module is hot-swappable when used within a properly configured ControlLogix system. This means the module can be inserted into or removed from the chassis while power is applied, without shutting down the entire system. However, hot-swapping should be done with caution — you must ensure that the controller is in a safe state, and it is strongly recommended to inhibit the module in the programming software (like Studio 5000) before removal or installation. Also, the system’s configuration must allow for electronic keying or be set to allow compatible keying to avoid faults. Hot-swap capability increases uptime and flexibility in maintenance and troubleshooting operations.

Question: What are voltage and current specs?
Date Update:20/06/2025
Answer:

Each output channel of the 1756-OB8 supports a voltage range of 10–30 VDC, with a nominal output of 24 VDC. The maximum current per point is 2 A, and the entire module can handle up to 8 A at 60°C ambient temperature. Surge current up to 4 A for 10 ms is supported, repeatable every second. The module’s backplane current consumption is 165 mA at 5.1 VDC and 2 mA at 24 VDC. Minimum load current per point is 2 mA, ensuring compatibility with low-consumption devices. Off-state leakage is limited to 1 mA, and voltage drop during on-state is a maximum of 1.2 V at 2 A.

Question: What are its isolation and temp specs?
Date Update:20/06/2025
Answer:

The 1756-OB8 is rated for operation in environments from 0°C to 60°C and storage from -40°C to +85°C. It tolerates relative humidity from 5% to 95%, non-condensing, and must be installed in environments free of corrosive gases and dust. Its isolation voltage is 50 V continuous between field-side and logic-side circuits. It provides basic protection against voltage spikes but should be used in conjunction with external fusing and surge suppression in critical applications. Proper grounding and shielding are also recommended to ensure stable operation in electrically noisy environments.

Question: Is 1756-OB8 still produced or replaced?
Date Update:20/06/2025
Answer:

Yes, the 1756-OB8 is currently still manufactured and supported by Rockwell Automation. It is part of the standard ControlLogix platform and widely used in both legacy and modern systems. However, for high-speed or safety-related applications, Rockwell also offers newer models with advanced diagnostics or output protection. Alternatives like the 1756-OB8EI provide enhanced electronic protection features. Migration to newer ControlLogix 5580 series I/O is also recommended for high-performance systems. When replacing or upgrading, ensure software and firmware compatibility with the controller.

IQElectro is not an authorized distributor.
IQElectro LLC (IQElectro) is NOT an Authorized Distributor or in any way affiliated with Rockwell Automation, Siemens, or any other Manufacturers. IQElectro is NOT an Authorized Dealer of this product. The product may be of older version, date codes, or design than that available from authorized dealers. As IQElectro is not an authorized dealer of this product, the Original Manufacturer's Warranty and Support DO NOT apply. IQElectro sells SURPLUS only and DOES NOT SELL SOFTWARE or FIRMWARE licenses For more detailed information, please refer to the full version of our disclaimer policy Disclaimer Policy.
Description / Specifications

Description 

The Allen-Bradley 1756-OB8 is an 8-point 24VDC digital output module for ControlLogix chassis, providing sourcing outputs in two isolated groups. Each channel operates within a 10–30VDC range with a nominal 24VDC signal level and supports up to 2 A per point. The module connects through the 1756-TBNH or 1756-TBSH removable terminal blocks and integrates into both local and distributed ControlLogix I/O systems.

 

 

Technical Specifications 

Condition New/Never Used Surplus
Brand Allen-Bradley
Category I/O Modules
Part Number 1756-OB8
Subcategory Digital Output Modules
Series ControlLogix
Module Type 24VDC Sourcing Output Module
Number of Outputs 8
Output Groups 2 groups of 4
Output Voltage Range 10–30VDC
Nominal Output Voltage 24VDC
Max Current per Point 2 A @ 60°C
Max Current per Module 8 A @ 60°C
Backplane Current (5.1V) 165 mA
Backplane Current (24V) 2 mA
Backplane Power 0.89 W
Power Dissipation 2.5 W @ 60°C
Isolation Voltage 50V continuous
Removable Terminal Blocks 1756-TBNH, 1756-TBSH
ON Signal Delay ≤1 ms
OFF Signal Delay ≤2 ms
Surge Current 4 A for 10 ms (1 s repeat)
Minimum Load Current 2 mA
Operating Temperature 0–60°C
Storage Temperature –40 to 85°C
Humidity 5–95% non-condensing
Enclosure None (requires ControlLogix chassis)

  

 

Information About 1756-OB8

The 1756-OB8 is part of the ControlLogix platform, offering a modular digital output solution with eight DC sourcing channels arranged in two groups of four. Its design incorporates solid-state output circuitry with configurable behavior in program and fault modes, enabling flexible operation in automation systems. The module is compatible with all standard ControlLogix chassis and supports rack-optimized, scheduled, and listen-only communication formats. Typical applications include controlling DC loads such as solenoids, relays, pilot devices, and interposing circuits within industrial control architectures requiring robust 24VDC output performance.

Key Features:

  • 8 sourcing outputs: Provides eight 24VDC output channels in two groups.
  • 10–30VDC operating range: Nominal 24VDC signal supports most industrial devices.
  • 2 A per point at 60°C: Suitable for medium-duty DC load control.
  • 8 A per module maximum: Supports aggregated current demands across channels.
  • Fast switching times: 1 ms ON and 2 ms OFF typical signal delay.
  • Compatible RTBs: Works with 1756-TBNH and 1756-TBSH removable terminal blocks.
  • ControlLogix backplane integration: Supports multiple communication formats including rack optimization.
  • Configurable fault and program states: Per-point selection of Hold Last State, ON, or OFF.
  • Continuous isolation voltage: Rated at 50V for noise and signal protection.
  • Minimal power consumption: Draws 165 mA at 5.1VDC and 2 mA at 24VDC from the backplane.
  • Wide environmental tolerances: Operates from 0–60°C with 5–95% non-condensing humidity.

The 1756-OB8 delivers the reliability and precision required for dependable digital output control in ControlLogix automation systems.

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