D-Link DEM-331R Gigabit BiDi Single-Mode 40 km SFP Transceiver

Make One Fibre Strand Work in Both Directions The DEM-331R is a 1000BASE-BX-U SFP transceiver for a compatible Gigabit switch or network interface. It connects over single-mode fibre using simplex lc connectivity, with a complementary DEM-331T at the far end. A single fibre carries transmit and receive traffic on different wavelengths, helping use existing fibre capacity efficiently. The rated maximum reach is 40 km, subject to compatible optics, fibre quality and the complete optical link budget. Highlights Optical Connection 1000BASE-BX-U for Gigabit Ethernet over single-mode fibre. Simplex LC. Complementary DEM-331T required at the remote end. Distance and Fibre 40 km. 9/125 µm single-mode fibre. Calculate optical loss and receiver limits before installation. Installation Hot-pluggable SFP form factor. 3.3 V power supplied by a compatible host slot. Check host support, firmware and operating limits. Key Features Choose the Optical Link for the Site 1000BASE-BX-U uses wavelength-division multiplexing over one single-mode fibre strand. The connector, wavelength, speed and fibre type must all match the complete link. A mechanically fitting module is not proof that a switch or network card supports its optical mode. Use the Rated Reach as a Design Limit The 40 km rating is a maximum design reach, not a guarantee for any cable of that length. Connector loss, splices, patching, fibre condition and the remote receiver affect the result. Measure and test the commissioned link rather than relying on distance alone. Match the Remote End Use DEM-331T at the opposite end of the strand. Its transmit and receive wavelengths complement this module, whereas two identical BiDi modules do not form the intended pair. Both host ports also need to support the required Ethernet speed and exact module. Keep Maintenance Modular The hot-pluggable SFP design allows replacement at the supported host port without restarting the entire switch. Removing the module still interrupts the traffic on that link. Follow the host’s installation procedure, handle the unit with appropriate ESD precautions and protect the optical connector from dust. Respect Optical and Environmental Limits Confirm the host and module operating conditions before installation. Long-reach optics may require attenuation on a short or low-loss link to avoid exceeding the receiver’s maximum input. Use an optical power meter and the documented transmit/receive limits to validate the installation. Complete the Link With the Correct Equipment This offer is one SFP transceiver. The host, fibre cable, patch panels and complementary remote module are separate. Select those parts as one link design, retaining a record of the installed module identity and optical measurements for future maintenance. Summary The DEM-331R provides a replaceable single-strand BiDi connection when its optical mode, cabling and supported host are selected together. Plan the remote end and optical budget before ordering, then verify the completed link so the installation has a clear, maintainable specification. Frequently Asked Questions Will It Work in Any SFP Slot?ExpandCollapse No. The host must explicitly support this module, its SFP form factor, Ethernet speed and optical mode. An SFP-shaped socket or the same brand name alone does not establish compatibility. Which Fibre Cable Does It Need?ExpandCollapse Use one 9/125 µm single-mode fibre strand with a simplex LC connection and the complementary BiDi module at the remote end. Is the Maximum Distance Guaranteed?ExpandCollapse No. The documented reach is 40 km. It depends on the complete optical path, fibre type and condition, connector/splice losses and receiver limits. Validate the installed link. Do I Need a Different Module at the Other End?ExpandCollapse Yes. Pair this model with DEM-331T; their transmit and receive wavelengths are complementary. Can a Long-Reach Module Be Used on a Short Cable?ExpandCollapse Only if the resulting optical power is within the receiver’s permitted range. Some short links require an appropriate attenuator. Check the exact transmit/receive specifications and measure the link before use. What Is Included?ExpandCollapse One DEM-331R transceiver. The host switch or interface, fibre cable, remote module and any required attenuation are separate. Keep the supplied module identification and host compatibility information with the installation record. Magbasa pa