1756-OF8K ControlLogix Conformal Coated 8-Channel Analog Output Module | Allen Bradley

Product Overview

The Allen Bradley 1756-OF8K serves as a high-density, chassis-based analog output module within the ControlLogix ecosystem. It provides eight high-resolution channels to drive field devices such as control valves, high-speed actuators, and variable frequency drives (VFDs). The "K" designation signifies a factory-applied conformal coating, which safeguards the internal circuitry against moisture, salt spray, and corrosive chemical vapors. This module bridges the gap between digital control logic and precise physical actuation in the most demanding industrial environments.

Technical Specifications

Engineering Advantages

• Corrosion Resistance via Conformal Coating: The 1756-OF8K features a specialized protective film (Conformal Coating). This barrier prevents "tin whiskers" and PCB corrosion in wastewater treatment, oil and gas, and chemical processing facilities where corrosive gases like $H_2S$ and $Cl_2$ typically degrade standard electronics.

• High-Speed Control Loop Performance: A settling time of just 2 ms ensures rapid signal response. This minimizes lag in critical PID loops, allowing the controller to maintain precise setpoints during high-speed machine transitions or volatile process fluctuations.

• Precision Actuation: 15-bit resolution provides granular control over field devices. In voltage mode, the module delivers increments as fine as 320 µV, while current mode offers 650 nA per bit, eliminating stepped movements in modulated control valves.

• Robust Drive Capability: The module drives current loads up to 750 Ω and voltage loads greater than 2000 Ω. This high drive strength enables long cable runs between the control chassis and the field device without sacrificing signal accuracy or integrity.

• Enhanced Electrical Safety: 250 V isolation protects the sensitive ControlLogix backplane and other chassis modules from electrical noise and ground loops originating in the field. This isolation maintains system uptime by localizing electrical faults to the individual module.

FAQs

• Is the 1756-OF8K provided as Brand New?

  Yes. We supply this module as 100% Brand New in original factory-sealed packaging. This guarantees the integrity of the conformal coating and ensures the hardware contains the latest manufacturing revisions.

• Can I use the 1756-OF8K to replace a standard 1756-OF8?

  Yes. The 1756-OF8K is fully backward compatible with the 1756-OF8. The "K" version offers superior environmental protection but shares the same technical performance and software configuration in Studio 5000.

• What Removable Terminal Block (RTB) does this module require?

  The 1756-OF8K requires a 20-position RTB. We recommend the 1756-TBNH (Cage Clamp) or 1756-TBSH (Spring Clamp) for secure field wiring. Note that RTBs are typically sold separately.

• Does this module require external power for the outputs?

  The module draws power from the ControlLogix backplane but requires a field-side power supply for the analog loops. Verify your chassis power supply capacity (MOD Power) during system design to accommodate the 5.8 W maximum consumption.