Honeywell 8939 Series Modules – 8939-HN

Technical Dossier

Product Details And Specifications

Honeywell 8939 Series Technical Notes

The Honeywell 8939 Series is a family of fiber optic communication and I/O interface modules developed for the Honeywell TDC 3000 / PlantScape / Experion PKS distributed control system architecture. These modules have been deployed across heavy industrial sectors including petroleum refining, chemical processing, nuclear power generation, and pulp & paper manufacturing. The 8939 Series serves as the physical-layer communication backbone between field controllers, I/O link interfaces, and the Universal Control Network (UCN), making it a critical component in plant-wide process automation infrastructure. Installed base across global refineries and chemical complexes remains substantial, with many facilities maintaining long-term operational continuity on TDC 3000 platforms well beyond the series' active production lifecycle.

The Evolution of 8939 Series Architecture

The 8939 Series was introduced as part of Honeywell's TDC 3000 platform expansion in the 1980s, designed to address the need for noise-immune, long-distance signal transmission between control cabinets and remote I/O enclosures. Fiber optic transmission was selected to eliminate ground loop interference and electromagnetic noise inherent in large industrial facilities.

Early variants of the 8939 family used ST-type fiber connectors and supported multimode 62.5/125 µm fiber at distances up to 1 km. As the TDC 3000 platform evolved into PlantScape and subsequently Experion PKS, the 8939 Series modules retained backward compatibility with existing fiber infrastructure, allowing facilities to upgrade control software layers without replacing physical cabling. This architectural decision extended the operational relevance of 8939 hardware well into the 2000s and 2010s.

By the mid-2010s, Honeywell formally transitioned new installations to the Experion PKS Series C I/O architecture, which uses Ethernet-based FOUNDATION Fieldbus and HART pass-through rather than dedicated fiber optic extender modules. The 8939 Series entered end-of-life status, with Honeywell ceasing active manufacturing. However, the installed base in brownfield facilities ensures continued demand for replacement and spare units through the secondary market.

8939 Series Full Catalog & Functionalities (SKU List)

The following SKUs represent the documented module range within the Honeywell 8939 Series. Modules are categorized by primary function:

Fiber Optic Extender / Communication Modules

• 8939-HN: Fiber optic extender module, UCN node interface, multimode fiber, ST connector
• 8939-HN-R: Redundant fiber optic extender module, dual-path UCN node interface
• 8939-LA: Local area fiber optic link adapter, short-range cabinet-to-cabinet
• 8939-LA-R: Redundant local area fiber optic link adapter
• 8939-FO: Fiber optic repeater module, signal regeneration for extended runs
• 8939-FO-R: Redundant fiber optic repeater, dual-channel signal path

I/O Link Interface Modules

• 8939-IO: I/O link fiber optic interface, connects I/O Link to UCN via fiber
• 8939-IO-R: Redundant I/O link fiber optic interface module
• 8939-IOP: I/O processor fiber optic interface, enhanced throughput variant
• 8939-IOP-R: Redundant I/O processor fiber optic interface

Network Communication Adapters

• 8939-NA: Network access fiber optic adapter, UCN-to-LCN bridge interface
• 8939-NA-R: Redundant network access fiber optic adapter
• 8939-NIM: Network interface module, UCN segment termination and management
• 8939-NIM-R: Redundant network interface module, dual UCN segment support

Power Supply & Ancillary Modules

• 8939-PS: Dedicated power supply module for 8939 Series backplane, 24 VDC regulated
• 8939-PS-R: Redundant power supply module, hot-swap capable
• 8939-BP: Backplane assembly for 8939 Series module mounting, 6-slot configuration
• 8939-BP-12: Extended backplane assembly, 12-slot configuration for high-density installations

Quality Control for the 8939 Series Range

The 8939 Series presents specific quality verification challenges due to its fiber optic transmission architecture and backplane bus communication design. DriveKNMS applies the following test protocol to all 8939 units prior to dispatch:

• Fiber Optic Port Inspection: ST connector ferrule inspection under 200x magnification. Optical power output measured with calibrated optical power meter against Honeywell factory specification (typically -15 dBm to -20 dBm transmit power at 820 nm wavelength).
• Backplane Bus Communication Test: Module is seated in a reference 8939-BP backplane and powered via 8939-PS. UCN communication handshake is verified using a TDC 3000 reference controller node.
• Firmware Revision Verification: EPROM or flash firmware revision is read and documented. Compatibility matrix against known TDC 3000 / Experion PKS software releases is checked.
• Thermal Cycling: Units are subjected to 0°C to 60°C thermal cycling over 4 hours to identify latent solder joint or component failures.
• Visual PCB Inspection: Full board inspection for corrosion, capacitor bulge, trace damage, and connector pin condition.
• Burn-In Test: 48-hour powered operation under nominal load prior to final packaging.