UDP Receive

Receive UDP packets from another UDP host on an Internet network

Libraries:
Simulink Support Package for LEGO MINDSTORMS EV3 Hardware
Simulink Coder Support Package for BeagleBone Blue Hardware / Communication
Simulink Support Package for Android Devices / Communication

Description

Receive UDP packets from the local network. The block output, data, emits UDP packet data as a one-dimensional vector of a specified data type. The block output, size, emits the size the data in the UDP buffer.

The data type of the block output, Data, depends on the Data type parameter. The data type of the block output, Size, is uint16.

While UDP Receive waits for new data to arrive, size emits a stream of zeros. When new data arrives, size changes to a non-zero value.

If you simulate a model that contains the UDP Receive block on your host computer (e.g., Simulation > Normal), and send UDP packets to that model from a board, the data output emits a disproportionately large number of zeros. This is because Simulink^® software simulates the model as a free-running application with a shorter period than the real-time application running on the board. In other words, the free-running simulation outputs zeros because it is waiting for the “slower” real-time application on the board to send data. If both applications were running on boards, this mismatch would not occur.

Note

If you are having trouble using UDP to communicate with a computer, investigate whether antivirus or firewall software might be blocking UDP traffic. If so, try configuring the software to allow UDP traffic for a specific IP port number.

Examples

Control LEGO MINDSTORMS EV3 Robot from Host Computer

Create a Simulink® model to communicate between the Host PC and the LEGO® MINDSTORMS® EV3 robot. The Simulink model running on the Host PC will exchange data with the EV3 brick and control the motion of the EV3 robot.

Open Model

Controlling LEGO MINDSTORMS EV3 Robot Using Raspberry Pi Sense HAT

Read the Accelerometer on Raspberry Pi® Sense HAT and use this data to control the movement of a LEGO® MINDSTORMS® EV3 robot.

Open Model

Ports

Output

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Data — Output port for data
[Nx1] array

The output port that emits the UDP packet data as a one dimensional vector of a specified data type.

Size — Size of the data in UDP buffer
scalar

The output port that emits the size of the data in the UDP buffer.

Data Types: uint16

Parameters

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Local IP port — Local IP port number used by the sending UDP host
25000 (default) | scalar

The number of the IP port on the local device, which can range from 1 to 65535. This value defaults to 25000. The local device is the board running the model.

Data type — Data type of the vector elements in the message output
uint8 (default) | scalar

This is the data type of the vector elements in the message output. Match the data type with the data input used to create the UDP packets.

Data size (N) — Number of data elements in each UDP packet
255 (default) | scalar

Set the number of data elements in each UDP packet. Match the data size used to create the UDP packets.

Sample time — Time frequency at which the block reads the port buffer
0.1 (default) | scalar

Specify how often this block reads the port buffer. Enter a value greater than zero.

Smaller values require the processor to complete the same number of instructions in less time, which can cause task overruns.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2017a