This function returns a session to the Default Resource Manager resource.
[status, sesn] = viOpenDefaultRM()
contains the return code of the operation.
unique logical identifier to a Default Resource Manager session.
The viOpenDefaultRM() function must be called before any VISA operations can be invoked. The first call to this function initializes the VISA system, including the Default Resource Manager resource, and also returns a session to that resource. Subsequent calls to this function return unique sessions to the same Default Resource Manager resource. When a Resource Manager session is passed to viClose(), not only is that session closed, but also all find lists and device sessions (which that Resource Manager session was used to create) are closed.