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Error 56 Occurs When Using TCP Listen VI in LabVIEW

Updated Nov 6, 2023

Reported In


  • LabVIEW Full
  • LabVIEW Base
  • LabVIEW Professional

Issue Details

I am using the TCP Listen VI and am getting Error 56: The network operation exceeded the user-specified or system time limit


This could occur if your TCP VIs are configured to return a machine name as opposed to an IP address and your server is configured to read IP addresses as opposed to machine names.

Here are a few possible solutions:

  1. Have the TCP VIs return an IP Address instead of a machine name. For more details, see the KB: Get TCP Listen and/or TCP Wait on Listener VI's to return an IP address
  2. Setup the name resolver for the network; how to do this may vary across networks.

This timeout error can also be caused by other parts of your code that aren't TCP related. If you are using reentrant VI's anywhere in your code, check to be sure that there are no race conditions or other factors that could be causing the TCP server to time out.

Additional Information

Note: A server configured to read machine names instead of IP addresses is said to perform name resolution; a similar terminology is used when configuring VIs to return machine names vs IP addresses, which is discussed in the KB:
Get TCP Listen and/or TCP Wait on Listener VI's to return an IP address