DS3800NFCF | Mark IV Fiber Optic Link Module

Description

Product Introduction

The DS3800NFCF is the single-channel version of the fiber optic communications board—the predecessor to the dual-channel NFCD series. The “F” in the suffix indicates fiber optic communications, and the “C” identifies this as a single-channel variant. The board mounts in the Mark IV rack and provides electrically isolated, noise-immune communication over distances up to 2 kilometers. It was used in installations where only one remote link was needed—typically connecting the Mark IV CPU to a single remote I/O cabinet or operator workstation.

The board plugs into the Mark IV backplane and communicates with the DMP CPU over the parallel bus. The fiber optic transceiver operates at 2Mbps with an 850nm LED-based transmitter. Compare this to the DS3800NFCD (dual-channel version of the same board). The NFCF is the same board as the NFCD but with only one fiber optic channel populated. If you only need a single link, this is the board you want. If you need two links, you need the NFCD. For most applications, the NFCD was preferred because it gave you a spare channel, but the NFCF was lower cost for single-link installations.

Key Technical Specifications

Compatible Replacement Models

Frequently Asked Questions (FAQ)

What’s the difference between the NFCF and the NFCD?
The NFCF is single-channel; the NFCD is dual-channel. The NFCF has one fiber optic transceiver; the NFCD has two. The boards are physically identical except for the populated components. If you need one link, the NFCF is sufficient. If you need two links (e.g., one to a remote I/O cabinet and one to an operator workstation), you need the NFCD. The NFCD can also be used with only one channel connected if you need a spare.

Can I use the NFCD as a replacement for the NFCF?
Yes, the NFCD is a direct drop-in replacement for the NFCF. If you install an NFCD in a system that previously used an NFCF, you can simply use Channel A (or Channel B) and leave the other channel disconnected. The Mark IV will only see the active channel. This is a common upgrade path—customers often replace a failed NFCF with an NFCD to gain redundancy.

Can I use single-mode fiber with this board?
No, the NFCF uses 850nm LED transceivers designed for multimode fiber. Single-mode fiber won’t work—the LED doesn’t have enough power to couple into the smaller core. You’ll need 62.5/125µm multimode fiber with ST connectors. If you have single-mode fiber installed, you’ll need a different board or a media converter.

What’s the maximum distance I can run with this board?
The NFCF is rated for 2km with 62.5/125µm fiber and a 3dB/km loss budget. In practice, we’ve seen it run up to 3km on good fiber with low connector loss. If you’re exceeding 2km, you should test the link before commissioning. The diagnostic LEDs on the board will indicate link quality—if the link is marginal, the Error LED will flash.

Is the fiber link redundant?
No, the NFCF has only one channel, so there’s no redundancy. If the fiber link fails, you lose communication. If you need redundancy, you’ll need two NFCF boards (in separate CPU racks) or the NFCD with a different architecture. The Mark IV doesn’t support automatic failover on the fiber links.

What’s the protocol used on the fiber link?
GE uses a proprietary protocol that’s not compatible with standard industry protocols like Profibus or Modbus. The NFCF communicates directly with the DMP CPU over the backplane—there’s no protocol stack for external devices. If you need to connect to non-GE equipment, you’ll need a gateway or a different communication board (like the NECA). The NFCF is for GE-to-GE communication only.

Can I hot-swap this board?
No. Mark IV backplanes are not hot-swappable. Pulling the NFCF with power applied can cause voltage spikes on the backplane. Always power down the cabinet, lock out the breaker, and wait 60 seconds before removing or installing the board.

What’s the most common failure mode on the NFCF?
We’ve serviced about 30 NFCF boards over the past six years. The most common failure is the LED transceiver—it degrades over time, reducing the optical power output. The symptom is intermittent link drops or the Link LED staying off. The fix is replacing the transceiver (a standard ST LED module). The second most common failure is the edge connector—corrosion from humidity. We clean it with a fiberglass brush and isopropyl alcohol. The board is repairable.

What’s your warranty and lead time?
We stock the NFCF in our Dallas and Houston warehouses. Lead time is 1-2 business days. We offer a 1-year warranty on functional defects. 30-day return window for unused boards—full refund minus shipping. We test every NFCF with a 24-hour burn-in and a fiber optic loopback test before shipping. The test report is included.

Is this board compatible with the Mark VIe?
No. The Mark VIe uses a completely different backplane architecture. This board is for Mark IV systems only. If you’re upgrading to Mark VIe, you’ll need new CPU and I/O boards. The NFCF won’t fit or function.

PACIFIC SCE904AN-002-01
GE VMIVME-7750
Foxboro P0973JN