Product Overview: The Allen-Bradley 1756-OX8I Isolated Relay Output Module
In industrial automation, isolating control signals from different voltage domains is critical to protect equipment and ensure reliable operation. The Allen-Bradley 1756-OX8I Isolated Relay Output Module provides a robust solution with eight individually isolated relay outputs, allowing mixed AC and DC loads in a single module. This module is part of the ControlLogix family and offers Form C contacts with normally open and normally closed configurations. With an operating voltage range of 10–265 VAC or 5–150 VDC, the 1756-OX8I can drive various output devices such as contactors, motor starters, and pilot lamps.
Technical Specifications and Performance Metrics
| Specification |
Value |
| Manufacturer |
Rockwell Automation |
| Brand |
Allen-Bradley |
| Part Number |
1756-OX8I |
| Series |
ControlLogix |
| Outputs |
8-Point Individually Isolated |
| Module Type |
Isolated Relay Output Module |
| Output Current |
2, 0.5, 0.25 Amps |
| Contact Output |
Form C contacts |
| Operating Voltage |
10-265 Volts AC, 5-150 Volts DC |
| Initial Contact Resistance |
100 mΩ @ 6V 1 A |
| Maximum Switching Frequency |
1 operation/3 s (0.3 Hz at rated load) |
| Mean Bounce Time |
1.2 ms |
| Removable Terminal Blocks |
1756-TBCH, 1756-TBS6H |
| Maximum Output Delay Time |
13 milliseconds |
| Expected Contact Life |
300 kHz resistive; 100 kHz inductive |
| Backplane Current at 5 Volts |
100 mA |
| Power Dissipation (Max) |
3.1 Watts at 60 Celsius |
| UPC |
10612598171474 |
| UNSPSC |
32151705 |
| Enclosure |
None |
| Isolation Voltage |
250V (continuous), basic insulation type, outputs-to-backplane, and output-to-output |
Real-World Applications and Use Cases
The Allen-Bradley 1756-OX8I Isolated Relay Output Module excels in applications requiring voltage isolation and mixed-load handling. For example, in a motor control center, the module can simultaneously drive a 120 VAC contactor and a 24 VDC indicator lamp on different outputs, eliminating the need for separate interface modules. This reduces panel space and wiring complexity, leading to lower installation costs and higher system reliability. Additionally, the long contact life (300 kHz resistive) ensures minimal maintenance intervention over the equipment’s lifespan.
System Compatibility and Integration
The 1756-OX8I is designed for the Rockwell Automation ControlLogix platform and installs directly into any 1756 local or remote chassis. It communicates over the backplane and requires no additional configuration beyond standard I/O mapping. Compatible removable terminal blocks include the 1756-TBCH and 1756-TBS6H, which simplify wiring and module replacement. For non-isolated applications, users can short the L1 connections using a jumper (1756-JMPR or equivalent).
Selection Guide and Purchasing Advice
When selecting the Allen-Bradley 1756-OX8I Isolated Relay Output Module, ensure your ControlLogix chassis has an available slot. Verify the operating voltage of your loads to confirm compatibility with the module’s 10–265 VAC / 5–150 VDC range. Order the appropriate removable terminal block separately if not already on hand. For genuine Allen-Bradley 1756-OX8I modules and reliable service, visit UBEST Automation at ubest101.myshopify.com.