UDP Receive

Receive UDP packets on a given IP port

• Library:

• DSP System Toolbox / Sources

• 

Description

The UDP Receive block receives UDP packets from an IP network port and saves them to its buffer. With each sample, the block outputs the contents of a single UDP packet as a data vector. The local IP port number on which the block receives the UDP packets is tunable in the generated code.

The generated code for this block relies on prebuilt .dll files. You can run this code outside the MATLAB^® environment or redeploy it, but you must account for the extra .dll files. The packNGo function creates a ZIP file that contains the pieces required to run or rebuild this code. For more details, see How To Run a Generated Executable Outside MATLAB.

Ports

Output

Message — Data received

vector

Data received by the UDP Receive block, returned as a one-dimensional vector of the data type specified in Data type for Message. If you select Message is complex, the block treats the received message as complex data.

This port is unnamed until you clear the Output variable-size signal parameter.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean
Complex Number Support: Yes

Length — Length of data packet

scalar

Length of the data packet received, returned as a scalar. This value is determined by the value of the Maximum length for Message parameter.

Dependencies

This port appears only when you clear the Output variable-size signal parameter.

Data Types: uint16

Parameters

Local IP port — Number of IP port

25000 (default) | scalar in the range [1, 65535]

Specify the IP port number on which to receive UDP packets. This parameter is tunable in the generated code but is not tunable during simulation.

On Linux^®, to set the IP port number below 1024, run MATLAB with root privileges. For example, at the Linux command line, enter sudo matlab.

Remote IP address ('0.0.0.0' to accept all) — IP address from which to accept packets

'0.0.0.0' (default) | IP address

Specify the IP address from which to accept UDP packets. Specify a specific IP address to block UDP packets from other addresses. To accept packets from any IP address, specify '0.0.0.0'.

Receive buffer size (bytes) — Size of buffer that receives UDP packets

8192 (default) | scalar in the range [1, 67108864]

Specify the size of the buffer, in bytes, that receives the UDP packets. Make the buffer large enough to avoid data loss caused by buffer overflows.

Maximum length for Message — Maximum length of output data

255 (default) | scalar

Specify the maximum length, in vector elements, of the data output vector. Set this parameter to a value equal to or greater than the data size of a UDP packet. The system truncates data that exceeds this length.

If you disable Output variable-size signal, the block output is the length specified by this parameter.

Data type for Message — Data type of message

uint8 (default) | single | double | int8 | int16 | int32 | uint16 | uint32 | boolean

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

Message is complex — Message data complexity

off (default) | on

Specify whether the block receives a message as complex data. Select this parameter to receive a message as complex data. Clear this parameter if a received message is real data.

Output variable-size signal — Message output that varies in length

on (default) | off

Specify whether your model supports signals of varying length. If your model supports signals of varying length, select this parameter. In that case:

• The output vector varies in length, depending on the amount of data in the UDP packet.

• The block emits the data vector from a single unlabeled output.

If your model does not support signals of varying length, clear this parameter. In that case:

• The block emits a fixed-length output that is the same length as specified by Maximum length for Message.

• If the UDP packet contains less data than the fixed-length output, the difference contains invalid data.

• The block emits the data vector from the Message output.

• The block emits the length of the valid data from the Length output.

If you disable this parameter, the block emits output that is the length specified by Maximum length for Message.

Sample time (seconds) — Frequency of calls to block

1 (default) | scalar

Specify the frequency at which the scheduler calls the UDP Receive block, in seconds. Enter a value greater than zero. In real-time operation, setting this parameter to a smaller value reduces the likelihood of dropped UDP messages.

Model Examples

Data Transmission Using UDP in Simulink

Transmit and receive a sine wave signal over UDP network.

Open Model

Block Characteristics

Data Types	Boolean | double | integer | single
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	yes
Zero-Crossing Detection	no

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using Simulink® Coder™.

Usage notes and limitations:

• The executable generated from this block relies on prebuilt dynamic library files (.dll files) included with MATLAB. Use the packNGo function to package the code generated from this block and all the relevant files in a compressed ZIP file. Using this ZIP file, you can relocate, unpack, and rebuild your project in another development environment where MATLAB is not installed. For more details, see How To Run a Generated Executable Outside MATLAB.

• The Local IP port parameter is tunable in the generated code, but not tunable during simulation. You can control the parameter tunability in the generated code in several ways. One of the ways is to configure the parameter as a tunable field of a global structure in the generated code. Other ways include applying a built-in storage class or custom storage class to a Simulink.Parameter object and using this object to set the value of the block parameter. For details, see Create Tunable Calibration Parameter in the Generated Code (Simulink Coder).

Version History

Introduced in R2010a