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Create UDP object


obj = udp('')
obj = udp('RemoteHost')
obj = udp('RemoteHost',RemotePort)
obj = udp(...,'PropertyName',PropertyValue,...)



The remote host.


The remote port.


A UDP property name.


A property value supported by PropertyName.


The UDP object.


obj = udp('') creates a UDP object, obj, not associated with a remote host. obj = udp('RemoteHost') creates a UDP object associated with remote host RemoteHost.

obj = udp('RemoteHost',RemotePort) creates a UDP object with remote port value, RemotePort. The default remote port is 9090.

obj = udp(...,'PropertyName',PropertyValue,...) creates a UDP object with the specified property name/property value pairs. If an invalid property name or property value is specified, the object is not created.


Start the echo server and create a UDP object.

u = udp('',4012);

Connect the UDP object to the host.


Write to the host and read from the host.

A = fread(u,10);

Stop the echo server and disconnect the UDP object from the host.



At any time, you can use the instrhelp function to view a complete listing of properties and functions associated with UDP objects.

instrhelp udp

When you create a UDP object, these properties are automatically configured:

  • Type is given by udp.

  • Name is given by concatenating UDP with the remote host name specified in the udp function.

  • RemoteHost and RemotePort are given by the values specified in the udp function.

You can specify the property names and property values using any format supported by the set function. For example, you can use property name/property value cell array pairs. Additionally, you can specify property names without regard to case, and you can make use of property name completion. For example, the following commands are all valid.

u = udp('','InputBufferSize',1024);
u = udp('','inputbuffersize',1024);
u = udp('','INPUT',1024);

The UDP object must be bound to the local socket with the fopen function. The default remote port is 9090. The default local host in multihome hosts is the system's default. The LocalPort property defaults to a value of [] and it causes any free local port to be used. LocalPort is updated when fopen is issued. When the UDP object is constructed, the Status property value is closed. Once the object is bound to the local socket with fopen, Status is configured to open.

The maximum packet size for reading is 8192 bytes. The input buffer can hold as many packets as defined by the InputBufferSize property value. You can write any data size to the output buffer. The data will be sent in packets of at most 4096 bytes.


To get a list of options you can use on a function, press the Tab key after entering a function on the MATLAB® command line. The list expands, and you can scroll to choose a property or value. For information about using this advanced tab completion feature, see Using Tab Completion for Functions.

Introduced before R2006a