DS3800NFDB | OEM GE Speedtronic Fiber Optic I/O

Description

Product Introduction

The DS3800NFDB is a dual-channel fiber optic communications board—the predecessor to the NFCD series. The “F” in the suffix indicates fiber optic communications, and the “D” identifies this as a dual-channel variant. The “B” is a manufacturing revision. The board mounts in the Mark IV rack and provides two independent, electrically isolated, noise-immune communication links over distances up to 2 kilometers. It was used in installations where two remote links were needed—typically connecting the Mark IV CPU to multiple remote I/O cabinets, or to a remote I/O cabinet and an operator workstation.

The board plugs into the Mark IV backplane and communicates with the DMP CPU over the parallel bus. Each of the two fiber optic channels operates at 2Mbps with an 850nm LED-based transmitter. Compare this to the DS3800NFCD (the later dual-channel board with the same basic functionality). The NFDB is the earlier generation—functionally identical to the NFCD, but with a slightly different component layout. For most applications, the NFDB and NFCD are interchangeable.

Key Technical Specifications

Compatible Replacement Models

Frequently Asked Questions (FAQ)

What’s the difference between the NFDB and the NFCD?
The NFDB is the earlier generation of the dual-channel fiber optic board. The NFCD is the later generation. They are functionally identical—both provide two fiber optic channels at 2Mbps with 850nm transceivers. The component layout may differ slightly, but the boards are interchangeable. If you have an NFDB and need to replace it, the NFCD is a direct drop-in replacement.

Can I use the NFDB with the newer long-haul fiber boards?
The NFDB is designed for standard 850nm short-wave fiber links up to 2km. It cannot communicate with long-haul boards that use 1300nm or 1550nm wavelengths. If you need to extend your fiber runs beyond 2km, you’ll need to upgrade both ends to long-haul boards (NFCD1G1H, NFCD1H1D, etc.).

Can I use single-mode fiber with this board?
No, the NFDB 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.

Is the fiber link redundant?
The NFDB has two channels (A and B), but they’re not redundant in the sense of failover. They’re two independent links to two different remote nodes—typically one for a remote I/O cabinet and one for an operator workstation. The Mark IV doesn’t support automatic failover on the fiber links—it’s a point-to-point protocol. For redundancy, you’d need two NFDB boards (in separate CPU racks) or a different architecture.

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 NFDB 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 NFDB is for GE-to-GE communication only.

Can I hot-swap this board?
No. Mark IV backplanes are not hot-swappable. Pulling the NFDB 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 NFDB?
We’ve serviced about 20 NFDB 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 NFDB 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 NFDB 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 NFDB won’t fit or function.

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