Ethernet IP Implicit Messaging with PLC on LabVIEW Is Failing

Updated Aug 3, 2023

Reported In


  • NI-Industrial Communications for Ethernet/IP

Issue Details

I am trying to connect with the PLC using the EtherNetIP Adapter.lvproj example from LabVIEW's native example and the explicit messages work fine while the implicit messages are not working. 
LabVIEW does not throw errors and my PLC timeouts.


In this scenario is likely that the implicit messaging is failing because the NI EtherNET IP drive it can only be the adapter (slave) not the scanner (master)
For this situation it's recommended to check the PLC or device's documentation and verify the device can be scanner as well as make sure that the device is set up correctly for implicit messaging.

If you verify that this is correct but it's still not working, try the following steps
  • Make sure that the firewall configuration is not blocking the messages. Implicit messaging uses UDP while explicit is TCP/IP.
  • Use some ethernet port monitoring tool to check the packages traffic when using explicit vs using implicit. One example is WireShark.
  • Make sure that other program or driver is not taking over the connection. This because if the PLC or device's driver is in the same computer where LabVIEW is, this can be interfering with the communication.

Additional Information

It's important to clarify that this does not mean that LabVIEW can't use implicit messaging but that it cannot start the communication.