Table Of Contents

TCP Create Listener (G Dataflow)

Last Modified: February 27, 2017

Creates a listener for a TCP network connection. Use the TCP Open Connection node to query the NI Service Locator for the port number registered with the service name.

Programming Patterns

net address

Network address to listen on. Specifying an address is useful if you have more than one network card, such as two Ethernet cards, and want to listen only on the card with the specified address. If you do not specify a network address, this node listens on all network addresses. Use the String to IP Address node to obtain the IP network address of the current computer.

This input supports scalar strings and unsigned 32-bit integers.

Default: 0


service name

Name you want to assign to the service. The node creates a known reference for the port number. If you specify a service name, this node registers the service name and the port number with the NI Service Locator.



Port number on which you want to listen for a connection. Wire 0 to port to dynamically choose an available TCP port that the operating system determines is valid for use.


timeout ms

Time, in milliseconds, that the node waits to complete before reporting a timeout error. A value of -1 indicates to wait indefinitely.

Default: 25,000 ms


error in

Error conditions that occur before this node runs. The node responds to this input according to standard error behavior.

Default: No error


listener ID

A network connection refnum that uniquely identifies the listener.


actual port

The port number the node used. If you wire 0 to the port input, LabVIEW dynamically chooses an available TCP port that the operating system determines is valid for use. If you wire a value other than zero to the input port, the output port number equals the input port number. As defined by the Internet Assigned Numbers Authority (IANA), valid port numbers are between the range of 49152 through 65535. Well-known ports range from 0 to 1023 and registered ports range from 1024 to 49151. However, not all operating systems follow the IANA standard. For example, Windows returns dynamic ports in the range from 1024 to 5000.


error out

Error information. The node produces this output according to standard error behavior.

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported

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