WiFi UDP Receive

Receive data from UDP host on wireless network

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

Libraries:
Simulink Support Package for Arduino Hardware / WiFi

Description

The WiFi UDP Receive block receives data from a UDP host on a wireless network. At each sample time, the block outputs data as a vector of the size specified in the Data size (N) parameter. The block receives data on the port number specified in the Local IP Port parameter. Match the port number specified in the Local IP Port parameter with the remote port number on the sending host.

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.

You can run a Simulink^® model containing WiFi UDP Receive 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.

Supported Hardware

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

WiFi Shield
MKR1000
MKR WIFI 1010
Nano 33 IoT

Limitations

When using ESP8266 hardware, a model can have only one WiFi TCP Receive, WiFi TCP Send, WiFi UDP Receive, or WiFi UDP Send block.
The maximum number of connections allowed for different ports on WiFi UDP Receive blocks and WiFi UDP Send blocks in a model is two for WiFi shield, four for MKR1000, and one for ESP8266. If the model uses External mode over Wi-Fi^® or includes a WiFi ThingSpeak Read block or WiFi ThingSpeak Write block, one UDP port is reserved for each from the maximum allowed connections.

Ports

Output

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Data — Output data
vector

At each sample time, the port outputs data as a vector of the size specified in the Data size (N) parameter. The data is received in little-endian format. To convert it to a big-endian format, do any of the following:

Place a Byte Reversal block immediately after the WiFi UDP Receive block.
Apply the swapbytes function in a MATLAB Function block and place the block immediately after the WiFi UDP Receive block.

For more information, see Outputs for Received Data.

Size — Number of data bytes received
scalar

At each sample time, the port outputs the number of bytes in the received data. For more information, see Outputs for Received Data.

Data Types: uint16

Parameters

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Local IP Port — IP port on receiving host from which data is received
`50001` (default) | [1 to 65,535]

Specify the port number of the application on which you want to receive data. Match the local port number with the remote port number on the sending host.

Data type — Data type of received data
`uint8` (default) | `double` | `single` | `int8` | `int16` | `uint16` | `int32` | `uint32` | `boolean`

Specify the type of the data the block receives from the sending host. The size of each element depends on its data type.

Data size (N) — Number of bytes in received data
`1` (default) | any positive integer

The number of bytes received at each sample time.

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

Target Hardware	ESP8266	WiFi Shield	MKR1000
Maximum Number of Received Bytes	40	64	1400

Sample time — Interval at which block reads data from sending host
`0.1` (default) | `-1` | any nonnegative value

When you set this parameter to -1, Simulink determines the best sample time for the block based on the block context within the model. When the hardware is ESP8266, the minimum sample time allowed is 0.01 seconds. Otherwise, it is 0.000001 seconds (1 microsecond).

More About

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Outputs for Received Data

This section explains the values at the output ports, with the following block parameters specified as:

Block Parameter	Value
Data type	`uint8`
Data size (N)	`4`

The values at the output ports vary depending on whether the length of the data received is less than, greater than, or equal to the length of requested data.

Length of UDP message received = Data size (N): The Data port outputs data as a vector of the size specified in the Data size (N) parameter. The Size port outputs the number of data bytes received.
Suppose that the length of the data received is 4. In this case, the Data port outputs a data vector of size 4. The Size port outputs 4.
Length of UDP message received < Data size (N): The Data port outputs data as a vector of the size specified in the Data size (N) parameter. All the empty spaces in the vector are filled with zeros. The Size port outputs the number of data bytes received (excluding zeros added to fill the vector).
Suppose that the length of data received is 3. In this case, the Data port outputs a data vector of size 4. The first three values in the vector are the bytes from the received data. The remaining space is filled with zero. The Size port outputs 3.
Length of UDP message received > Data size (N): The Data port outputs a data vector of the size specified in the Data size (N) parameter. The vector contains only the first N bytes from the received data. The remaining data bytes are dropped. The Size port outputs the number of data bytes received (including the output data bytes and the dropped data bytes).
Suppose that the length of data received is 5. In this case, the Data port outputs a data vector of size 4. The vector contains only the first 4 bytes from the received data. The remaining data byte is dropped. The Size port outputs 4 + 1 = 5.

Version History

Introduced in R2014a

WiFi UDP Receive