Product Overview
The Allen-Bradley 1756-OH8I is a high-performance ControlLogix isolated output module engineered for demanding industrial automation environments. As part of the ControlLogix series, this module provides 8-point individually isolated 120V DC sinking/sourcing outputs, delivering precise and reliable control for your discrete output applications. Whether you are managing solenoids, contactors, or indicator lamps, the 1756-OH8I ensures clean switching and robust performance.
Key Features & Benefits
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8 individually isolated outputs – each point is isolated to prevent cross-talk and enhance system reliability.
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120V DC sink-source capability – flexible wiring accommodates both sinking and sourcing configurations.
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Wide operating voltage range – 90-146V DC ensures stable operation even with fluctuating supply.
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High current handling – 2A per point and 8A per module at 60°C.
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Removable terminal blocks – supports 1756-TBCH and 1756-TBS6H for easy wiring and maintenance.
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Robust environmental tolerance – operates from 0 to 60°C with 5-95% relative humidity.
Technical Specifications
Below are the key technical specifications of the Allen-Bradley 1756-OH8I, sourced directly from the manufacturer's data:
| Parameter |
Value |
| Manufacturer |
Rockwell Automation |
| Brand |
Allen-Bradley |
| Part Number / Catalog No. |
1756-OH8I |
| Series |
ControlLogix |
| Module Type |
Isolated Output Module |
| Outputs |
8-Point Individually Isolated |
| Voltage |
120 Volts DC Sink-Source |
| Operating Voltage Range |
90-146 Volts DC |
| Maximum Output Current Rating - Point |
2 Amps at 60°C |
| Maximum Output Current Rating - Module |
8 Amps at 60°C |
| Power Dissipation (Max) |
3.3 Watts at 60°C |
| Backplane Current at 5 Volts |
210 milliamps |
| Removeable Terminal Block(s) |
1756-TBCH, 1756-TBS6H |
| Isolation Voltage |
50 Volts Continuous |
| Enclosure |
None (Open Style) |
| UPC |
10612598171443 |
Applications & Use Cases
The 1756-OH8I is ideal for a wide range of industrial control applications where reliable discrete output switching is critical. Typical use cases include:
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Material handling systems – controlling conveyor motor starters and diverters.
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Process control – actuating valves and solenoids in chemical or food processing lines.
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Machine tools – switching coolant pumps, spindle drives, and auxiliary equipment.
Thanks to its 120V DC output capability and high per-point current, the module handles demanding loads with ease, reducing the need for interposing relays.
Installation & Setup Guidance
Installing the 1756-OH8I is straightforward. Mount the module into any ControlLogix chassis slot, then connect the removable terminal block (1756-TBCH or 1756-TBS6H). Ensure that the power supply voltage stays within the 90-146V DC range. For sinking outputs, connect the load between the output point and the positive supply; for sourcing, connect between the output and the negative supply. Always follow the wiring diagram provided in the user manual to avoid misconnection.
Maintenance & Reliability
To ensure long-term reliability, periodically inspect the terminal block connections for tightness and signs of corrosion. The module's open-style enclosure allows for good airflow, but keep the surrounding environment free of excessive dust and moisture. The 1756-OH8I is designed to withstand operational vibration of 2G at 10-500Hz and shock up to 20G, making it suitable for harsh industrial settings. With proper care, this module delivers dependable service for years, minimizing downtime and maintenance costs.
Selection Guide & Purchasing Advice
When selecting the 1756-OH8I, verify that your ControlLogix chassis has an available slot and that the backplane current draw (210mA at 5V) is within your system's capacity. Consider the removable terminal block options (1756-TBCH or 1756-TBS6H) based on your wiring preferences. For genuine, quality-tested automation spares, PLC Source PRO offers the Allen-Bradley 1756-OH8I with reliable availability and competitive pricing.