When you insert an IO Configuration file into a TestStand sequence, TestStand creates a copy of the configuration file in the step you specify. When you run the sequence, the step creates sessions for the InstrumentStudio-configured instruments and applies the configuration to the new sessions.
These created sessions are automatically stored in local variables in TestStand. You can then pass the session from the variable to automation code in Action steps, apply a new configuration to the existing session using the variable, or use the session in a Sweep loop to configure the sequence of values for certain attribute in each instrument.
For more information on using TestStand, refer to TestStand documentation on ni.com.