Description
The Allen-Bradley 1756-OF4 is a 4-channel analog output module designed for the ControlLogix platform, engineered to convert digital controller values into proportional voltage or current control signals for industrial actuators, valves, and final control elements.
In field deployments, this module regulates process variables by supplying continuous control signals to proportional devices, supporting multi-loop control architectures compliant with IEC 61131 standards.
Technical Specifications
| Parameter | Value |
| Manufacturer | Rockwell Automation (Allen-Bradley) |
| Product Family | ControlLogix (Bulletin 1756) |
| Catalog Number / Model | 1756-OF4 |
| Module Type | Analog Output Module |
| Number of Outputs | 4 single-ended channels |
| Output Signal Ranges | ±10 V, 0 to 10 V, 0 to 20 mA, 4 to 20 mA |
| Resolution | 15 bits plus sign (binary) across specified ranges |
| Backplane Current Draw | 200 mA at 5.1 V DC; 150 mA at 24 V DC |
| Total Backplane Power | Approx. 4.8 W |
| Enclosure Protection | IP20 (open-style chassis module) |
| Operating Temperature | 0 to +60 °C |
Procurement and Availability
- Condition: New Surplus / Factory Sealed / Refurbished Tested options available upon request.
- Lead Time: 1 to 3 business days for stock items; verify factory allocation for legacy components.
- Warranty: 12-month standard warranty from date of shipment.
- Price: Indicative market pricing applies. Price subject to market conditions; contact us for a firm quote.
Integration and Compatibility Notes
The 1756-OF4 module installs into any standard 1756 ControlLogix chassis slot and requires a compatible Removable Terminal Block (RTB), such as the 1756-TBNH or 1756-TBSH, for field wiring terminations.
- Loop Power Configuration: Current output channels require an external loop power supply connected to the appropriate terminals on the RTB. Verify voltage drop limits for 4 to 20 mA current loops (maximum loop resistance typically 600 ohms at 20 mA).
- Shield Grounding: Connect shielded twisted-pair cables to a dedicated earth ground bus at the panel entry point to reduce susceptibility to electromagnetic interference (EMI).
- Software Configuration: Configured natively through Studio 5000 Logix Designer or RSLogix 5000 software environment using standard controller tags.
Frequently Asked Questions
Q: Are the 4 output channels individually isolated? A: No. The 1756-OF4 features channel-to-backplane isolation, but the outputs share a common return path. Verify external device isolation if driving multiple separate unisolated loads.
Q: What happens to the analog output values if the controller faults or switches to program mode? A: Output behavior during a controller fault or communication loss can be configured in Studio 5000 to hold last state, freeze to a user-defined safe value, or revert to zero.
Q: Which terminal block matches this module? A: The module accepts standard Bulletin 1756 RTBs (such as 1756-TBNH screw-clamp or 1756-TBSH spring-clamp terminal blocks), which are sold separately.
