Nowadays most people make one model for all their aircrafts. Technically speaking, this works as long as your aircrafts all use the same switch order. If, like me, you fly drones, flight controller planes, receiver planes and rc cars. You need different models to have the right channel output and the right mixing. With ELRS, using a bind phrase is the most common way of binding your devices, but that means that all your models use the same bind phrase. This means you could be using the wrong model and have a crash or poor performance because the setup is not the same. Using model match can save the headache of having a potential crash.
Shown below is the Model setup menu where you would assign a number for model match.
The parameters stored per-Receiver number are:
Packet Rate The RC update frequency (500Hz, 250Hz, etc)
Telem Ratio Telemetry ratio (Off, 1:128, 1:64, etc)
Switch Mode Method for sending switches to the receiver
Model Match Enable the model match feature (see below)
Max Power Transmitter output power level
Dynamic Power Enable Dynamic Power switching
ExpressLRS uses a binding phrase, which means the transmitter will connect to any receiver built with that binding phrase. Model Match is a feature which prevents a full connection if the Model Match number does not match. In this mode, the receiver will connect to the handset, but no data will be sent from the receiver to the flight controller. This allows a user to force that the model selected in OpenTX only connects to a specific receiver, for example preventing using a quad OpenTX model definition with a fixed wing model.
The terms Receiver number (set in OpenTX/EdgeTX) and Model Match number (set in the receiver) are used interchangeably here-- they are the same.
If the Model Match option is Off, then only receivers with no Model Match number (255) can be connected. If the Model Match option is On, then the Receiver number configured in the external module configuration (as shown in the image above) must match the Model Match number stored on the receiver module for the receiver and transmitter to fully connect.
The implementation follows this set of rules for handling half connections / full connections
|
TX ModelMatch |
TX Receiver ID |
RX Model ID |
Result |
|
Off |
Any |
Off |
Connects / Communicates as usual |
|
Off |
Any |
A |
Connects but does not communicate to FC |
|
On |
Any |
Off |
Connects but does not communicate to FC |
|
On |
A |
A |
Connects / Communicates as usual |
|
On |
B |
A |
Connects but does not communicate to FC |
In summary, using a single model for all aircraft can lead to significant risks when flying various types, such as drones and planes, which may require different setups. The Model Match feature provided by ExpressLRS is useful for enhancing safety and performance by ensuring that the selected model corresponds correctly with the intended receiver. By implementing Model Match, users can avoid potential crashes and ensure that their configurations are accurate, thereby improving the overall flying experience. This approach protects against the pitfalls of using the wrong model and underscores the importance of tailored setups in the world of RC.