WiFi UDP Send

R2026b

Send data to UDP host on wireless network

• 

WiFi UDP Send block

To add a block to a model, double-click the canvas and start typing the block name. Then, select the block from the list.

Libraries:
Simulink Support Package for Arduino Hardware / WiFi

Description

Add-On Required: This feature requires the Simulink Support Package for Arduino Hardware add-on.

The WiFi UDP Send block sends data to a UDP host over a wireless network. The block sends data from the port number specified in the Local IP Port parameter. Specify the IP address and the port number of the receiving host in the Remote IP address and the Remote IP Port parameters.

The block supports transmission of both fixed-length and variable-length UDP packets.

You can run a model containing the WiFi UDP Send block in connected IO mode on Arduino^® boards.

For more information about the fixed ports and the allocated pins for the block, see Pin Mapping for Arduino Timer-Independent Blocks.

Note

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

Supported Hardware

You can use the WiFi UDP Send block only with the following hardware:

• ESP8266

• WiFi Shield

• MKR1000

• MKR WIFI 1010

• Nano 33 IoT

• ESP32–S3 series (Arduino compatible)

• ESP32–WROOM (Arduino compatible)

• ESP32–WROVER (Arduino compatible)

Limitations

• When using ESP8266 hardware, a model can have only one of these blocks: WiFi TCP/IP Receive, WiFi TCP/IP Send, WiFi UDP Receive, WiFi UDP Send block.

• The maximum number of connections allowed for different ports on WiFi UDP Receive and WiFi UDP Send blocks in a model is two for WiFi shield, four for boards with on-board Wi-Fi^®, and one for ESP8266. If the model uses external mode over Wi-Fi or includes a WiFi ThingSpeak Read or WiFi ThingSpeak Write block, one UDP port is reserved for each from the maximum allowed connections.

Ports

Input

Port_1 — Input data

vector

The block accepts data as an N-by-1 array. The block sends this data over a wireless network to the receiving host. The data is sent in little-endian format. To convert it to a big-endian format, do any of the following:

• Place a Byte Reversal block just before the WiFi UDP Send block.

• Apply the swapbytes function in a MATLAB Function block, and place the block just before the WiFi UDP Send block.

The maximum number of bytes that can be sent by this block at each time step is shown in the table.

Target Hardware	ESP8266	WiFi Shield	Arduino On-board Wi-Fi Boards
Maximum Number of Sent Bytes	2048	64	1400

Data Types: int8 | uint8 | int16 | uint16 | int32 | uint32 | single | double | Boolean

Parameters

Remote IP address — Remote IP address of host to which data is sent

192.168.1.2 (default) | any valid IP address

Specify the remote IP address of the host to which the data is sent. To broadcast data to all the receiving hosts, specify 255.255.255.255.

Remote IP Port — Remote IP port on host to which data is sent

50002 (default) | [1 to 65,535]

Specify the port number of the application on the host to which data is sent. Match the remote port number with the local port number on the receiving host.

Local IP Port — IP port on sending host from which data is sent

50001 (default) | [1 to 65,535]

Specify the port number of the application on the target from which data is sent.

Enable variable length data — Enable variable length packet transmission

off (default) | on

Allow the block to process variable-length UDP data instead of a fixed-length payload. The block adjusts to the actual number of bytes available during the current write operation.

Enabling the option adds a two-byte length prefix at the start of the UDP payload. This prefix encodes the actual data size, allowing the receiver to reliably reconstruct the message length and correctly parse the packet contents even when the payload varies at runtime.

To use variable-length UDP transmission and reception in a model, you must enable this parameter on both the WiFi UDP Receive and WiFi UDP Send blocks.

Version History

Introduced in R2014a

R2026b: Add support for variable length UDP payloads

The block transmits both fixed and variable length UDP packets.