Essential RC Airplane Telemetry Technology


When trying to perfect their performance, RC hobbyists, pros, and even amateurs will frequently rely on RC Airplane Telemetry devices and systems, since a capable pilot should learn to better use his/her physical abilities and available technology, searching for ways to not only develop their own skills with practice but also to get as many as possible useful information about their vehicle’s behavior while flying.

With that in mind, one telemetry essential yet basic product that is highly recommended is the FrSky Smart Port RPM and Temperature Sensor. Like many other sensors from FrSky, this one also works with the Smart Port interface and, when installed properly in association with an S.Port enabled receiver, it can send the acquired data to its respective transmitter ‘s digital Telemetry Radio System.

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FrSky Smart Port System

So… what is Smart Port? For those of you that don’t have a clue or never even heard about it in the first place: the S.Port (Smart Port) is a signal wire full-duplex digital transmission interface provided by FrSky Electronic Co., Ltd. and it was developed for the 2nd generation of FrSky systems.

Every S.Port enabled device - sound modules, display modules, sensors (such as the one we are talking about here), and any other device that works with a data interface that is in line with FrSky S.Port protocol - can be directly plugged in and arranged however the user desires, making RC components/device setup much easier than conventional multi-wire looms.

To sum it up, the Smart Port system offers this flexible and superior possibility of daisy-chaining several different components with high precision and without the need of a sensor-hub or other dataset. It is smaller, easier, and faster (approximately 6 times more than a conventional “hub system”), perfect for RC Airplane Telemetry.

RPM and Temperature Sensor

The FrSky Smart Port RPM and Temperature Sensor is a two-in-one telemetry device for RC Airplanes that can measure the RPM of brushless motors and also read the temperatures of other components besides the motor itself, such as ESCs and BECs, glow and gas engine cylinder heads, batteries, mufflers, voltage regulators, tailpipes and even ambient air!

Considering how important it is to know your RC airplane’s motor’s RPM and the temperature of critical components (for performance and safety reasons), the functions in the sensor will prove to be very useful. The RPM reading range (for a 2-pole brushless motor) is 1,000-30,000 rpm and the temperature can range from -20°C to 250°C (degrees Celsius) - 4°F - 482°F (degrees Fahrenheit).


One can notice in the image above that the sensor is small and lightweight (only 8g), which is ideal since it is a device that will not necessarily be used in every flight. 

Mounting and Setting up

As expected from a product made by FrSky, its users will find it straightforward and easy to install by following these steps:

Attach one end of the Temperature Sensor (TEMS-01) to your ESC and the other end to one of the two corresponding sets of pins (T1 or T2) that are mounted on the PCB (Printed Circuit Board).

Next, connect the sensor to any couple of wires from the brushless motor using the supplied JST connector.

Finally, connect the RPM sensor to the receiver (and/or other FrSky sensors) via Smart Port, then turn it on by linking your battery to the receiver.

Now to finish setting up:

Check the number of Pole Pairs in your brushless motor.

Enter Pole Pairs setting mode long-pressing the key until the Red LED is on.

Then, push the key repeatedly until you’ve got the correct number (in Binary) set on the little 4-digit display (0 to 3).

Power off the receiver after set.

Thus, as you can see, this entire installation and setup procedure is indeed quite simple and relies only on the push button and LED status indicator. For more detailed instructions and schematics, check the product manual on FrSky’s website.


Operation Specifics

Do bear in mind that this technology was designed to work with FrSky’s Smart Port interface, meaning that it is only compatible with Smart Port enabled receivers, such as the X8R, X6R, and X4R. Also, before using, please consider that although it can work with motor wires’ voltage range of 7.4 - 44.4V, that is, motors that run on 2S to 12S LiPo batteries, this sensor was made to operate at 4 -10V.


This RPM/temperature sensor can also be used simultaneously with other FrSky Smart Port enabled sensors, including the variometer, airspeed, GPS, lipo voltage, and current sensors, since all of those can daisy chain with each other through their Smart Port.

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