RC Radios: Protocols, Channels and Receivers

The transmitter stays on the ground and the receiver is installed in the model. They need compatible radio protocols, while receiver outputs must suit the servos or flight controller. Confirm the whole control chain before comparing screens, feel and switch counts.

Choose a stick mode, then count the channels

Mode 2 commonly places throttle on the left and Mode 1 on the right; the other axes also vary by mode. Choose a mode that suits you and keep the simulator and aircraft consistent. Changing modes may also require adjusting gimbal centering and friction mechanisms.

Traditional fixed-wing aircraft commonly use aileron, elevator, throttle and rudder as four basic controls. Flaps, retracts, independent ailerons and flight modes require more channels. Radio channel count, physical receiver sockets and available functions are not equivalent.

Common controls; actual channel numbers depend on model configuration
Function	Purpose	Setup considerations
Aileron / roll	Roll the aircraft left or right	Surface direction, travel and dual-servo mixing
Elevator / pitch	Raise or lower the nose	Surface direction, neutral position and mechanical travel
Rudder / yaw	Control yaw	Coordinate turns; does not replace ailerons
Throttle	Control power output	Minimum value, throttle cut and failsafe action
Auxiliary channels	Flight modes, flaps, landing gear and more	Match switch positions to receiver-side functions

EdgeTX, ELRS and CRSF operate at different layers

EdgeTX is the transmitter’s operating software for model settings, mixes and the interface. ExpressLRS (ELRS) is a radio control link system. An EdgeTX transmitter does not necessarily contain ELRS; check its internal RF module or external module.

PWM, SBUS and CRSF describe receiver outputs to servos or flight controllers. Fixed-wing installations driving servos directly need suitable PWM outputs. Serial receivers normally connect to a flight controller; their ports are not arbitrary ordinary servo sockets.

Two devices using 2.4 GHz are not automatically bind-compatible. Check the radio protocol, hardware versions, firmware compatibility and regional settings, then choose a receiver according to the manufacturer’s instructions.

Confirm which version you are buying

The RadioMaster Pocket, for example, comes in ELRS and CC2500 configurations. Appearance alone does not identify the radio protocol. Different configurations with the same transmitter name need not support the same receivers.

Compare gimbal size, switches and knobs, display, model storage, trainer functions and USB simulator support. A large screen helps with complex settings; a compact radio is easier to carry. Feel and aircraft requirements determine which suits you.

For simulator-only practice, a USB simulator controller can provide basic inputs. It is different from an RC transmitter that sends radio control signals. Confirm your intended use before buying.

RadioMaster: Pocket Versions, RF Options and Manual

After binding, check channels and surfaces

Binding establishes a connection, not a correctly configured model. For ELRS, transmitter modules and receivers also need compatible firmware major versions and other requirements. Follow current official instructions for a binding phrase or the relevant binding procedure.

Create a separate model profile for each aircraft. Remove propellers, then check channel order, direction, travel, center positions and switches. Orders such as AETR and TAER differ. If a flight controller is fitted, verify the axes and switches it actually receives, not just the moving channel bars on the transmitter.

ExpressLRS: Compatibility and Binding

Configure throttle cut, failsafe and return-to-home separately

Throttle cut intentionally disables power; failsafe handles a lost radio link. Automatic return-to-home requires a flight controller, positioning and correct navigation settings. A receiver with failsafe does not automatically provide return-to-home.

Remove propellers and safely verify the actual response to signal loss, ensuring dangerous throttle is not maintained. Whether the receiver or flight controller handles the response depends on the complete system. Fixed-wing and multirotor aircraft cannot share a blindly copied failsafe setup.

Perform the manufacturer’s reduced-power range check before flight. Confirm antenna installation, link status and power supply. Receiver supply voltage shown in telemetry is not necessarily flight battery voltage.

ExpressLRS: Link Checks Before the First Flight

Use a separate simulator model when connecting to a computer

A radio supporting USB Joystick can connect by data cable, after which you calibrate and map channels in the simulator. Use a dedicated simulator profile to avoid changing real-aircraft mixes, failsafe and travel settings.

EdgeTX recommends disabling internal and external RF modules in USB joystick mode. USB charging support does not guarantee simulator data support on that port. Check the port’s purpose and transmitter manual.

EdgeTX: USB Joystick Mode