Agilent Technologies E2094S, Руководство пользователя, Страница: 29 / 146

Programming with VISA
3
Agilent VISA User’s Guide 29
VISA Attributes
Attributes are associated with resources or sessions . You can use
attributes to determine the state of a resource or session, or to set a
resource or session to a specified state.
For example, you can use the viGetAttribute function to read the state
of an attribute for a specified session, event context, or find list. There
are read only (RO) and read/write (RW) attributes. Use the
viSetAttribute function to modify the state of a read/write attribute for
a specified session, event context, or find list.
The pointer passed to viGetAttribute must point to the exact type
required for that attribute ( ViUInt16 , ViInt32 , etc.). For example, when
reading an attribute state that returns a ViUInt16 , declare a variable of
that type and use it for the returned data. If ViString is returned, allocate
an array and pass a pointer to that array for returned data.
Example: Reading a VISA Attribute This example reads the state
of the VI_ATTR_TERMCHAR_EN attribute and changes it if it is false.
ViBoolean state, newstate;
newstate=VI_TRUE;
viGetAttribute(vi, VI_ATTR_TERMCHAR_EN, &state);
if (state err !=VI_TRUE) viSetAttribute(vi,
VI_ATTR_TERMCHAR_EN, newstate);
Memory Access
(MEMACC) Generic, GPIB-VXI,
VXI Address space of a
memory-mapped bus such as
the VXIbus.
VXI Mainframe
Backplane
(BACKPLANE) Generic, GPIB-VXI,
VXI (GPIB-VXI
BACKPLANE not
supported) VXI-defined operations and
properties of each backplane
in a VXIbus system.
TCPIP Socket
(SOCKET) Generic, TCPIP Operations and properties of
a raw network socket
connection using TCPIP.
Table 4 Resource Classes Supported by Agilent VISA (continued)