In this article, we will look into the types of FrSky Sensors, what a sensor is, how it works, and whether or not you need one in your system. FrSky has been built an ecosystem of sensors and add-ons to their line of receivers and radio controllers for a more versatile selection of accessories in their portfolio.


What is a sensor & why use one?


According to Wikipedia, “In the broadest definition, a sensor is a device, module, machine, or subsystem whose purpose is to detect events or changes in its environment and send the information to other electronics”.


Similarly, in the RC field, sensors are devices that we use to measure quantifiable measurements such as voltage, current, temperature, RPM, etc. These values are universal and do not change from place to place nor time to time when they are measures, which is why they are quantifiable - they can be measured as a particular value regardless of external factors.


As mentioned previously, sensors measure values and in the RC world, we need to receive real-time values of a lot of variables, from vital parts of the craft like engine temperature or motor RPM, etc.


How does a sensor work?


A sensor usually works by reacting to physical conditions by changing their electrical properties.

Simply put, a sensor converts a physical property such as heat, light or in RC - temperature, RPM, current, etc. into electrical signals which will then be processed and sent across to your transmitter via SmartPort (In case of FrSky Sensors) or to your Flight Controller.


This data can be very vital in long-range flights to keep tabs on your craft and its health levels.


Types of FrSky Sensors


FrSky has a plethora of sensors with SmartPort connectivity options for their line of receivers. We will get into a few types of these sensors from FrSky below.


1.    MLVSS - Battery Voltage Sensor

This is a classic battery voltage sensors with support up to a 6S battery. It basically connects to your battery via the balance plug and outputs the voltage to your receiver via the SmartPort plug. You can find more information on it from the link below:


2.    FAS100S - Current Sensor

The FAS100S is a current sensor designed to measure large current from 1 to 100 Ampere. It is mainly directed to large scale models where there is a high power draw. It can take up to 14S Li-Po voltage and also has the ability to measure temperature with its two temperature probes. All the data including the current, voltage, and temperature will be sent via the SmartPort to the receiver which will then be relayed to your transmitter.

You can learn more about it from


3.    Vari-N - Atmospheric Pressure/Altitude Sensor


The Vari-N is a variometer sensor that detects the change in environmental pressure. As altitude increases, pressure decreases and so you can calculate the altitude of the craft with this sensor value.

The altitude rate formula as provided by FrSky is:  (Output DA Voltage -1.65)/1.65=Altitude Rate speed/10.24.


Keep in mind that the sensor value can be affected by a sudden change in atmospheric pressure due to gust of winds etc. The sensor data is sent via SmartPort to the sensor hub or the receiver.

You can learn more about it from


4.    FSH-01 - FrSky Sensor Hub

The FSH-01 is an important tool if you have a lot of sensors that need to be attached to your receiver for telemetry data. It is basically a sensor “hub” which connects to multiple sensors from FrSky like - GPS sensor, RPM sensor, Fuel sensor, etc. and acts as an information gathering and processing center to monitor and send telemetry data to your FrSky DHT-U or receiver.

You can find more information regarding it at




You can get details about the entire sensor lineup from FrSky from this link:


In this article, we have learned about what a sensor is, how it works and a few sensor examples from FrSky, and how they interact to provide you with real-time telemetry data from your craft.

Although these sensors from FrSky were used before, now most of these are outdated as modern Flight Controllers are the ones usually sending the telemetry data from its own onboard sensors. In either way, you can use some of these sensors for some discrete applications or planes where a flight controller is absent.