Transferring Data Between Windows and the RT Target

Use remote communication methods to transfer data between VIs running on Windows and VIs running on the RT target of an NI Real-Time Hypervisor system. You can use the virtual Ethernet connection provided by the NI Real-Time Hypervisor. You also can use one or more additional physical Ethernet cards.

Using Remote Communication Methods

Whether you use the virtual Ethernet connection or an actual Ethernet card, you can use standard LabVIEW remote communication methods to transfer data between RT VIs and Windows VIs running on a hypervisor system.

Using the Virtual Ethernet Connection

The virtual Ethernet connection provided by the NI Real-Time Hypervisor transfers data within memory on the system instead of over an Ethernet cable. However, the virtual Ethernet connection works with standard network communication protocols just like an actual Ethernet connection. Although Windows and the RT target actually run on the same computer, the virtual Ethernet connection allows them to function as network peers as if they were separate computers.

Note  Because the virtual Ethernet connection uses a link-local IP address, Windows reports a warning about "limited connectivity" on the virtual Ethernet connection. This warning is expected and does not indicate a problem.

You can use the virtual Ethernet connection if the system does not have a secondary Ethernet card or if you need to avoid interference from external network traffic.

Note  The virtual Ethernet connection does not support TCP offloading. TCP offloading requires a physical Ethernet card to compute checksums to verify TCP packets. Because the virtual Ethernet connection does not use a physical Ethernet card, Windows must compute the TCP checksums, which requires additional CPU overhead.

Enabling and Disabling the Virtual Ethernet Connection

Complete the following steps to enable and disable the virtual Ethernet connection.

Note  If you plan to use a direct physical Ethernet connection between Windows and the RT target, you must disable the virtual Ethernet connection to prevent link-local IP conflicts.

1. Right-click Virtual Ethernet in the device tree of the NI Real-Time Hypervisor Manager and select Properties to display the Device Properties dialog box.
2. Place a checkmark in the Enable Virtual Ethernet checkbox to enable the virtual Ethernet connection or remove the checkmark to disable the virtual Ethernet connection.

When the virtual Ethernet connection is enabled, you can configure the virtual Ethernet connection in Windows just like any other Ethernet connection.

Tip  To avoid CPU overhead and prevent warning dialogs, ensure that the firewall is disabled on the virtual Ethernet connection. Because the virtual Ethernet connection is an inherently private connection between two operating systems on a single computer, the conventional reasons for enabling a firewall do not apply to the virtual Ethernet connection.

Using Additional Ethernet Cards

You can use additional Ethernet cards instead of or in addition to the virtual Ethernet connection. For example, if you do not want to use the virtual Ethernet connection, you can connect two physical Ethernet cards directly to communicate between Windows and the RT target.

Maximizing Throughput Between RT and Windows

Transferring data between Windows and the RT target through a network router introduces network traffic delays that can decrease throughput and increase jitter. Whether you use dedicated Ethernet cards or the virtual Ethernet connection, you can transfer data with higher throughput and less jitter by using a dedicated, direct connection.

Connecting the Virtual Ethernet Connection to a Physical Ethernet Connection

You can create a network bridge in Windows to connect two Ethernet connections. For example, you can connect the virtual Ethernet connection to a physical Ethernet connection hosted by Windows. By creating such a connection, you can connect the RT target to the external network even if you do not have a separate physical Ethernet card assigned to the RT target.

Creating a Network Bridge

Complete the following steps to create a network bridge.

• Select Start»Control Panel in Windows to display the Control Panel window.
• Double-click Network Connections to display the Network Connections window.
• Select both network connections simultaneously.
• Right-click one of the selected network connections and select Bridge Connections from the shortcut menu.

After you complete these steps, the network bridge appears under a Network Bridge heading in the Network Connections window. After you create the network bridge, you no longer can configure settings on the individual network connections. Instead, you can configure these settings on the network bridge itself by right-clicking the network bridge and selecting Properties from the shortcut menu to display the Network Bridge Properties dialog box.

Configuring Network Connections for a Hypervisor System

The following table summarizes common network configurations for NI Real-Time Hypervisor systems.