Configure Ethernet cDAQ on Computer With Two Network Ports

Updated Jul 31, 2023



  • cDAQ-9181
  • cDAQ-9191
  • cDAQ-9188

I have an Ethernet cDAQ device connected to a host computer that has two network ports. When both ports are used (the cDAQ device and another Ethernet connection), I sometimes lose communication with the cDAQ device. How can I configure my system to maintain reliable connections on both ports?

Make sure you are meeting all the rules for configuring systems with multiple network interface cards (NIC), such as having each port on a different subnet.

By default, Windows automatically evaluates each interface on a system, which can lead to inconsistent ranking, if two interfaces are given equal metrics. To force consistency, you can disable the Automatic Metric feature.
  1. Open the Windows Control Panel, and navigate to Network Connections.
  2. Right-click a network interface, then click Properties.
  3. Select Internet Protocol Version 4 (TCP/IPv4) >> Properties.
  4. On the General tab, click Advanced.
  5. On the IP Settings tab, uncheck Automatic metric, and enter a value in the Interface metric field.

To prioritize the port through which your cDAQ device connects, you should give it a lower metric than your second interface. For example, you could enter interface metrics of 10 for the port that handles communication with the cDAQ device and 20 for the other interface. 

If you are still having trouble communicating with your cDAQ device, you might need to configure the device’s Ethernet adapter with a static IP address. Configure a Static IP Address on Ethernet cDAQ​  shows the steps to take.

Additional Information

When multiple network interfaces are installed in a system, they are given performance and reliability rankings, or interface metrics. These rankings are used to establish a preferred route for Ethernet traffic. If the port through which your cDAQ device is connected is not the preferred route, it might take longer to establish contact with the device, and certain NI software services could time out, interrupting communication with your cDAQ.