“Forward Open” Message Reject When I Trying to Communicate With the Device by EtherNet/IP in LabVIEW

Updated Jun 17, 2022

Reported In

Hardware

  • CompactRIO Controller
  • CompactRIO Single-Board Controller
  • Industrial Controller
  • PXI Controller
  • Smart Camera

Software

  • LabVIEW

Driver

  • NI-Industrial Communications for Ethernet/IP

Issue Details

I use a third-party device that supports EtherNET/IP communication. Regardless of what LabVIEW code I use, even when using the shipping example "EtherNETIP Adapter.lvproj" I can't communicate with the device. For setting up the communication I use the "Forward Open" message, but I don't receive any response from the device. 

Solution

When you use the EtherNET/IP protocol there have to be two devices one of which has to act as a Master and the other one as a Slave. The Master is the Scanner and the Slave is the Adapter. The Master's role is to start the communication.
NI-Industrial Ethernet/IP enables the LabVIEW system to communicate as an EtherNET/IP Class 1 adapter device on an Ethernet/IP network. This means that you can't start the communication using the NI-Industrial Communication EtherNET/IP, thus meaning that sending the "Forward Open" message which starts the communication will not be possible. 

If you have to use implicit cyclic communication (an initiative of the communication is proceeded by the device controlled by software), the LabVIEW system that uses NI-Industrial EtherNET/IP can only be the slave and the other device has to initiate the communication. If the other device is not capable to be Master then the communication will not be possible as there can't be two slaves in EtherNET/IP.
If there is a possibility to use asynchronous communication, then it is possible to use explicit messaging (an initiative of communication is proceeded by the external device, connected to the system via EtherNET/IP) and the communication will take place.