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Opening an Instrument Session The Agilent 816x VXIplug&play Instrument Driver
Agilent 8163A/B, 8164A/B & 8166A/B Mainframes, Fifth Edition 227
Opening an Instrument Session
To control an instrument from a program, you must open a communication
path between the computer/controller and the instrument. This path is
known as an instrument session, and is opened with the function
ViStatus hp816x_init( ViRsrc InstrDesc, ViBoolean id_query, ViBoolean reset,
ViPSession instrumentHandle );
Instruments are assigned a handle when the instrument session is
opened. The handle, which is a pointer to the instrument, is the first
parameter passed in all subsequent calls to driver functions.
The parameters of the function hp816x
_init include:
•
ViRsrc InstrDesc: the address of the instrument
•
ViBoolean id_query: a Boolean flag which indicates if in-system verifica-
tion should be performed.
Passing VI_TRUE (1) will perform an in-system verification; passing
VI_FALSE (0) will not.
If you set
id_query to false, you can use the generic functions of the in-
strument driver with other instruments.
•
ViBoolean reset: a Boolean flag which indicates if the instrument should
be reset when it is opened.
Passing VI_TRUE (1) will perform a reset when the session is opened;
passing
VI_FALSE (0) will not perform a reset,
•
ViPSession instrumentHandle: a pointer to an instrument session.
InstrumentHandle is the handle which addresses the instrument, and is
the first parameter passed in all driver functions.
Successful completion of this function returns
VI_SUCCESS