VTI Instruments
44
EMX-75XX Index
catch (_com_error &e)
{
::MessageBox(NULL, e.Description(), e.ErrorMessage(),
MB_ICONERROR);
}
catch (...)
{
// handle errors here, depending on needs
}
Return 0;
}
Option Strings
The VTEX drivers provide option strings that can be used when Initializing an instrument. The
option string values exist to change the behavior of the driver. The following options strings are
available on VTI IVI drivers:
•
Simulate
: Allows the user to run a program without commanding switch card or instruments.
This option is useful as a debugging tool.
•
Cache
: Per the IVI specification, this option “specifies whether or not to cache the value of
attributes.” Caching allows IVI drivers to maintain certain instrument settings to avoid
sending redundant commands. The standard allows for certain values to be cached always or
never. In VTI IVI-drivers, all values used are of one of these types. As such, any values
entered have no effect.
•
QueryInstrumentStatus
: Queries the instrument for errors after each call is made. As
implemented in the VTI IVI drivers, instruments status is always queried regardless of the
value of this property.
•
DriverSetup
: Must be last, and contains the following properties:
o
Logfile
: Allows the user to specify a file to which the driver can log calls and other data.
o
Logmode
: Specifies the mode in which the log file is opened. The allowed modes are:
•
w
: truncate s the file to zero length or creates a text file for writing.
•
a
: opens the file for adding information to the end of the file. The file is created if it
does not exist. The stream is positioned at the end of the file.
o
LogLevel
: Allows the user to determine the severity of a log message by providing a
level-indicator to the log entry.
o
Slots
: This is the most commonly used option and it allows for a slot number or a slot
number and a card model to be specified.
"Slots=(2)" - Just slot 2.
"Slots=(2=EMX_75XX)" - slot and card model
"Slots=(2,3)" - Multiple slots
•
InterchangeCheck
: Boolean option that enables/disables IVI Interchangeability checking. As
implemented in the VTI IVI drivers, values entered for this property have no effect.
•
RangeCheck
: Boolean option that enables or disables driver validation of user-submitted
values. As implemented in the VTI IVI drivers, validation of user inputs
is always performed
at the firmware level regardless of this property’s value.
•
RecordCoercions
: Boolean option that enables driver recording of coercions. As
implemented in the VTI IVI drivers, coercions are handled in the firmware and cannot be
recorded.
