Technical data

38 Programmer’s Guide
4 Programming Example
Addressing a Session
As seen in the previous section, the rsrcName parameter in the viOpen
function is used to identify a specific device. This parameter is made up
of the VTL interface name and the device address. The interface name is
determined when you run the VTL Configuration Utility. This name is
usually the interface type followed by a number. The following table
illustrates the format of the rsrcName for the different interface types:
The following describes the parameters used above:
Closing a Session
The viClose function must be used to close each session. You can
close the specific device session, which will free all data structures that
had been allocated for the session. If you close the default resource
manager session, all sessions opened using that resource manager will
be closed.
Since system resources are also used when searching for resources
(viFindRsrc) or waiting for events (viWaitOnEvent), the
viClose function needs to be called to free up find lists and event
contexts.
board
This optional parameter is used if you have more than one interface of the same
type. The default value for board is 0.
VXI logical address This is the logical address of the VXI instrument.
primary address This is the primary address of the USB device.
secondary address This optional parameter is the secondary address of the USB device. If no
secondary address is specified, none is assumed.
INSTR This is an optional parameter that indicates that you are communicating with a
resource that is of type INSTR, meaning instrument.