Table Of Contents
TCP Open Connection (G Dataflow)
Opens a TCP network connection using a specified address and port or service name.
To free up system resources once data transmission is complete, use the TCP Close Connection node to close the connection.
Programming Patterns
address
The network address with which you want to establish a connection. This address can be an IP address or a hostname.
If you do not specify an address, this node establishes a connection to the local computer.
remote port or service name
The port or name of the service on the server that you want to establish a connection with.
If the server you attempt to establish a connection with has been assigned a service name, wire a service name to this input to query the NI Service Locator for the port number that is associated with the service name. Otherwise, wire a port number to this input.
If you wire a value of 0 to this input, this node returns an error.
What Is the NI Service Locator?
The NI Service Locator stores a list of registered service names and returns a corresponding port number to clients that query for a particular service name.
A client can use a service name to query the NI Service Locator and obtain the port number associated with that service name. Thus, a client does not need to know the port number of a registered service in order to request that service.
The NI Service Locator runs as a background service and requires no user interaction.
Querying the NI Service Locator for Registered Services
Wire the name of the service that you want to request to the TCP Open Connection or the UDP Write node. The node queries the NI Service Locator for the port number associated with that service name.
timeout ms
Time, in milliseconds, that the node waits to complete before returning a timeout error. A value of -1 indicates to wait indefinitely.
Default: 60,000 ms (1 minute)
error in
Error conditions that occur before this node runs.
The node responds to this input according to standard error behavior.
Standard Error Behavior
Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.
Default: No error
local port
The local port number that the client uses to establish a connection with the server.
If you wire a value of 0 to this input, the operating system dynamically selects an unused port.
Some servers allow connections with clients that use port numbers only within a specific range.
Default: 0
connection ID
A network connection refnum that uniquely identifies the connection. Use this value to refer to this connection in subsequent node calls.
error out
This node can return the following error codes.
| 56 | The network operation exceeded the user-specified or system time limit. |
| 62 | The system caused the network connection to be aborted. |
| 63 | The server rejected the connection. This usually means that there is no active listener on the server. |
| 64 | The network connection is not yet established. |
| 66 | The network operation was closed by the peer. |
Standard Error Behavior
Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.
Where This Node Can Run:
Desktop OS: Windows
FPGA: Not supported
Web Server: Not supported in VIs that run in a web application