Allen-Bradley 1756-OA8 ControlLogix Digital AC Output Module
The 1756-OA8 is an 8-channel discrete AC output module designed for the Allen-Bradley ControlLogix platform, featuring two independent groups of four outputs each. Operating across a voltage range of 74 to 265 VAC (nominal 120/240 VAC), this module provides reliable switching control for industrial loads with flexible grouping options for separate AC supply levels.
Module Overview and Specifications
The 1756-OA8 module delivers dependable AC load control with dual-group architecture, enabling flexible integration into standard ControlLogix chassis and remote I/O configurations.
| Parameter | Specification |
|---|---|
| Model | 1756-OA8 |
| Brand | Allen-Bradley |
| Series / Product Line | ControlLogix |
| Module Type | Digital AC Output Module |
| Number of Outputs | 8 discrete outputs (2 groups of 4) |
| Operating Voltage Range | 74–265 VAC (47–63 Hz) |
| Nominal Output Voltage | 120 / 240 VAC (50–60 Hz) |
| Current per Point (Max) | 0.5 A @ 60 °C (140 °F) |
| Current per Group (Max) | 2 A @ 60 °C (140 °F) |
| Continuous Current per Module (Max) | 5 A @ 30 °C (86 °F) linear derating; 4 A @ 60 °C (140 °F) linear derating |
| Minimum Load Current per Point | 10 mA |
| Surge Current per Point | 20 A for 43 ms (repeatable every 2 s at 60 °C) |
| OFF-State Leakage Current | 3 mA per point (max) |
| Output Delay Time | 9.3 ms @ 60 Hz; 11 ms @ 50 Hz |
| Backplane Current Draw | 200 mA @ 5.1 VDC; 2 mA @ 24 VDC |
| Power Dissipation (Max) | 5.1 W @ 60 °C (140 °F) |
| Isolation Voltage | 50 V continuous |
| Compatible Removable Terminal Blocks (RTB) | 1756-TBNH, 1756-TBSH, 1756-TBCH, 1756-TBSH |
| Weight | 1.50 lbs (0.68 kg) |
Group Architecture and Power Management
The eight output channels are split into two independent I/O groups (Group 0 and Group 1) with four points each. Because the terminal commons are not internally connected between groups, you can power each group with different AC voltage levels (for example, operating Group 0 at 120 VAC and Group 1 at 240 VAC), provided both fall within the 74 to 265 VAC operational threshold.
Wiring and Chassis Compatibility
Field wiring is terminated using compatible Removable Terminal Blocks such as the 1756-TBNH, 1756-TBSH, or 1756-TBCH. The modular RTB design allows wires to be terminated securely without wiring directly to the module itself, simplifying installation and hardware replacement. The module fits into a single slot of any standard ControlLogix chassis (such as 1756-A4, 1756-A7, 1756-A10, 1756-A13, or 1756-A17) in either local or distributed I/O architectures.
Frequently Asked Questions
Q: Can the two groups on the 1756-OA8 operate at different AC voltages simultaneously? A: Yes, because the two output groups feature separate terminal commons that are not internally connected, one group can operate at 120 VAC while the other operates at 240 VAC.
Q: Are the output channels internally fused? A: No, the module does not include internal channel fusing. It is recommended to install external fuses matched to the continuous point current rating to protect field wiring and connected loads.
Allen-Bradley 1756-OA8 ControlLogix Digital AC Output Module
Allen-Bradley 1756-OA8 ControlLogix Digital AC Output Module
The 1756-OA8 is an 8-channel discrete AC output module designed for the Allen-Bradley ControlLogix platform, featuring two independent groups of four outputs each. Operating across a voltage range of 74 to 265 VAC (nominal 120/240 VAC), this module provides reliable switching control for industrial loads with flexible grouping options for separate AC supply levels.
Module Overview and Specifications
The 1756-OA8 module delivers dependable AC load control with dual-group architecture, enabling flexible integration into standard ControlLogix chassis and remote I/O configurations.
| Parameter | Specification |
|---|---|
| Model | 1756-OA8 |
| Brand | Allen-Bradley |
| Series / Product Line | ControlLogix |
| Module Type | Digital AC Output Module |
| Number of Outputs | 8 discrete outputs (2 groups of 4) |
| Operating Voltage Range | 74–265 VAC (47–63 Hz) |
| Nominal Output Voltage | 120 / 240 VAC (50–60 Hz) |
| Current per Point (Max) | 0.5 A @ 60 °C (140 °F) |
| Current per Group (Max) | 2 A @ 60 °C (140 °F) |
| Continuous Current per Module (Max) | 5 A @ 30 °C (86 °F) linear derating; 4 A @ 60 °C (140 °F) linear derating |
| Minimum Load Current per Point | 10 mA |
| Surge Current per Point | 20 A for 43 ms (repeatable every 2 s at 60 °C) |
| OFF-State Leakage Current | 3 mA per point (max) |
| Output Delay Time | 9.3 ms @ 60 Hz; 11 ms @ 50 Hz |
| Backplane Current Draw | 200 mA @ 5.1 VDC; 2 mA @ 24 VDC |
| Power Dissipation (Max) | 5.1 W @ 60 °C (140 °F) |
| Isolation Voltage | 50 V continuous |
| Compatible Removable Terminal Blocks (RTB) | 1756-TBNH, 1756-TBSH, 1756-TBCH, 1756-TBSH |
| Weight | 1.50 lbs (0.68 kg) |
Group Architecture and Power Management
The eight output channels are split into two independent I/O groups (Group 0 and Group 1) with four points each. Because the terminal commons are not internally connected between groups, you can power each group with different AC voltage levels (for example, operating Group 0 at 120 VAC and Group 1 at 240 VAC), provided both fall within the 74 to 265 VAC operational threshold.
Wiring and Chassis Compatibility
Field wiring is terminated using compatible Removable Terminal Blocks such as the 1756-TBNH, 1756-TBSH, or 1756-TBCH. The modular RTB design allows wires to be terminated securely without wiring directly to the module itself, simplifying installation and hardware replacement. The module fits into a single slot of any standard ControlLogix chassis (such as 1756-A4, 1756-A7, 1756-A10, 1756-A13, or 1756-A17) in either local or distributed I/O architectures.
Frequently Asked Questions
Q: Can the two groups on the 1756-OA8 operate at different AC voltages simultaneously? A: Yes, because the two output groups feature separate terminal commons that are not internally connected, one group can operate at 120 VAC while the other operates at 240 VAC.
Q: Are the output channels internally fused? A: No, the module does not include internal channel fusing. It is recommended to install external fuses matched to the continuous point current rating to protect field wiring and connected loads.
