FE50MKxR 650 nm DC-50 MBd 50 m OptoLock® POF Transceiver

The two variants are electrically identical except for the logic polarity of the receiver’s output. FE50MKNR provides a non-inverted TTL/CMOS output (output is HIGH when light is received), whereas FE50MKIR has an inverted output (output is LOW when light is received). This allows you to choose the device that matches your system’s logic convention without additional inverters.

Terminating a fibre is very simple with the OptoLock® interface. You cut the plastic optical fibre cable (typically 1 mm core with 2.2 mm jacket) cleanly to the desired length and then insert the bare end directly into the OptoLock port on the module. The transceiver’s built-in latching mechanism will lock the fibre in place. No special connectors, polishing, or crimping are required – the fibre is held securely by the OptoLock housing, ensuring correct alignment with the internal optics. If needed, the fibre can be released by depressing the latch to remove or reposition it.

The FE50MKxR transceivers can operate from either a 5 V DC or 3.3 V DC supply, giving flexibility to work with different systems. The module’s input and output are TTL/CMOS logic compatible, so they can connect directly to standard digital circuits (like microcontroller GPIO pins, UART/USART, etc.) without level shifters. This means if your system already uses 3.3 V or 5 V logic, the transceiver will interface seamlessly at those levels.

Yes. The transceiver’s data rate range of DC to 50 MBd covers many popular industrial communication protocols. It can handle low-speed serial links (e.g. RS-232) up through mid-speed fieldbus networks such as RS-485/MODBUS, CAN bus (typically up to 1 Mbps), and even Profibus (which runs up to 12 Mbps). As long as the protocol’s baud rate is 50 Mbaud or below, the FE50MKxR can transmit the data over POF. This makes it suitable for isolating and extending these communication links in electrically noisy environments while maintaining protocol performance. Keep in mind that very high-speed protocols like 100 Mb Ethernet require a faster OptoLock model (the 250 Mbps version), but for all those listed, this 50 MBd transceiver is sufficient.

Under typical conditions, you can achieve around 50 metres of link length using standard 1 mm core step-index POF at the full 50 MBd data rate. This assumes good quality fibre, proper termination (clean cut), and nominal operating conditions. In a worst-case scenario (for example, at temperature extremes or with fiber attenuation at the high end of its spec), the reliable distance may reduce to roughly 20–30 metres. If you require longer reach, using a lower data rate can sometimes improve the distance, or you may need to switch to a higher-performance fibre optic solution. For most in-building industrial and automotive uses, a 50 m span is sufficient and within the capability of the FE50MKxR series.

Yes. The transmitter uses a 650 nm resonant-cavity LED which emits red light that is visible to the human eye (a dull red glow). Importantly, it is classified as Class 1 eye-safe under IEC 60825-1, meaning under normal operation conditions it does not pose a hazard to eyesight. This allows you to work with the fibre and transceiver without special laser safety precautions. The visible red light is actually an advantage during setup: you can see light at the end of the fibre or through the OptoLock port, which helps in verifying that the link is active and aligned properly.

Yes. The transceiver includes an RSSI (Received Signal Strength Indicator) output pin on the receiver. This analog output gives a measure of the optical signal level being received. By monitoring the RSSI voltage, a system can determine if a fibre link is present and gauge its signal margin or quality. For example, a microcontroller’s ADC could read the RSSI value to raise an alert if the signal drops (indicating a possible fibre disconnection, severe bending, or degradation). This feature can be very useful for diagnostics and maintenance, helping predict failures or misalignments in the optical link.

Plastic optical fibre transceivers find use in industrial and commercial systems where electrical isolation and noise immunity are important. Common examples include factory automation networks (connecting sensors, actuators, PLCs, and motor drives across noisy plant floors), industrial robotics (where moving joints benefit from flexible, light fibre cables), and power electronics or renewable energy systems (isolating communication between high-voltage sections and control units). They are also used in transportation systems (like in-vehicle or train communications) where vibrations and EMI are concerns. In general, these modules are chosen whenever you need a reliable short-distance data link that won’t be affected by electromagnetic interference and where copper wiring might introduce ground loops or safety issues. By using a POF transceiver, you get the robustness of fibre optics with the convenience of an easy, field-terminable connection.