TestStand installs and registers separate 32-bit NI Session Manager and 64-bit NI Session Manager servers on computers running 64-bit Microsoft Windows, even when you install only 32-bit TestStand. The 64-bit Session Manager works similarly to the 32-bit Session Manager. However, you cannot share session handles the out-of-process Session Manager creates between 32-bit processes and 64-bit processes because different servers generate the 32-bit session handles and 64-bit session handles. For example, if 64-bit TestStand calls a 32-bit LabVIEW VI, you cannot use session handles created in the LabVIEW VI in 64-bit TestStand or vice versa. Similarly, you cannot share handles between 32-bit TestStand and 64-bit TestStand when one instance of TestStand uses remote execution to invoke the other instance of TestStand.