Instrument Control Toolbox

visa

Create a VISA object

Syntax

• obj = visa('vendor','rsrcname')
  obj = visa('vendor','rsrcname','PropertyName',PropertyValue,...)
  

Arguments

'vendor'	A supported VISA vendor.
'rsrcname'	The resource name of the VISA instrument.
'PropertyName'	A VISA property name.
PropertyValue	A property value supported by PropertyName.
obj	The VISA object.

Description

obj = visa('vendor','rsrcname') creates the VISA object obj with a resource name given by rsrcname for the vendor specified by vendor. If an invalid vendor or resource name is specified, an error is returned and the VISA object is not created. The supported values for vendor are given below.

Vendor	Description
agilent	Agilent Technologies VISA
ni	National Instruments VISA
tek	Tektronix VISA

The format for rsrcname is given below for the supported VISA interfaces. The values indicated by brackets are optional.

Interface	Resource Name
GPIB	GPIB[board]::primary_address::[secondary_address]::INSTR
VXI	VXI[chassis]::VXI_logical_address::INSTR
GPIB-VXI	GPIB-VXI[chassis]::VXI_logical_address::INSTR
RSIB	RSIB::remote_host::INSTR (provided by NI VISA only)
Serial	ASRL[port_number]::INSTR

The rsrcname parameters are described below.

Parameter	Description
board	Board index (optional - defaults to 0)
chassis	VXI chassis index (optional - defaults to 0)
port_number	Serial port number (optional - defaults to 1)
primary_address	Primary address of the GPIB instrument
remote_host	Host name or IP address of the instrument.
secondary_address	Secondary address of the GPIB instrument (optional - defaults to 0)
VXI_logical_address	Logical address of the VXI instrument

obj = visa('vendor','rsrcname','PropertyName',PropertyValue,...) creates the VISA object with the specified property names and property values. If an invalid property name or property value is specified, an error is returned and the VISA object is not created.

Remarks

At any time, you can use the instrhelp function to view a complete listing of properties and functions associated with VISA objects.

• instrhelp visa
  

You can specify the property names and property values using any format supported by the set function. For example, you can use property name/property value cell array pairs. Additionally, you can specify property names without regard to case, and you can make use of property name completion. For example, the following commands are all valid.

• v = visa('ni','GPIB0::1::INSTR','SecondaryAddress', 96);
  v = visa('ni','GPIB0::1::INSTR','secondaryaddress', 96);
  v = visa('ni','GPIB0::1::INSTR','SECOND', 96);
  

Before you can communicate with the instrument, it must be connected to obj with the fopen function. A connected instrument object has a Status property value of open. An error is returned if you attempt a read or write operation while obj is not connected to the instrument. You cannot connect multiple VISA objects to the same instrument.

Creating a VISA-GPIB Object

When you create a VISA-GPIB object, these properties are automatically configured:

• Type is given by visa-gpib.
• Name is given by concatenating VISA-GPIB with the board index, the primary address, and the secondary address.
• The BoardIndex, PrimaryAddress, SecondaryAddress, and RsrcName values are given by the values specified during object creation.

Creating a VISA-VXI Object

When you create a VISA-VXI object, these properties are automatically configured:

• Type is given by visa-vxi.
• Name is given by concatenating VISA-VXI with the chassis index and the logical address specified in the visa function.
• The ChassisIndex, LogicalAddress, and RsrcName values are given by the values specified during object creation.

Creating a VISA-GPIB-VXI Object

When you create a VISA-GPIB-VXI object, these properties are automatically configured:

• Type is given by visa-gpib-vxi.
• Name is given by concatenating VISA-GPIB-VXI with the chassis index and the logical address specified in the visa function.
• The ChassisIndex, LogicalAddress, and RsrcName values are given by the values specified during object creation.
• The BoardIndex, PrimaryAddress, and SecondaryAddress values are given by the visa driver after the object is connected to the instrument with fopen.

Creating a VISA-Serial Object

When you create a VISA-serial object, these properties are automatically configured:

• Type is given by visa-serial.
• Name is given by concatenating VISA-Serial with the port specified in the visa function.
• The Port and RsrcName values are given by the values specified during object creation.

Example

Create a VISA-serial object connected to serial port COM1 using National Instruments VISA interface.

• vs = visa('ni','ASRL1::INSTR');
  

Create a VISA-GPIB object connected to board 0 with primary address 1 and secondary address 30 using Agilent Technologies VISA interface.

• vg = visa('agilent','GPIB0::1::30::INSTR');
  

Create a VISA-VXI object connected to a VXI instrument located at logical address 8 in the first VXI chassis.

• vv = visa('agilent','VXI0::8::INSTR');
  

Create a VISA-GPIB-VXI object connected to a GPIB-VXI instrument located at logical address 72 in the second VXI chassis.

• vgv = visa('agilent','GPIB-VXI1::72::INSTR');
  

See Also

Functions

fclose, fopen, instrhelp, instrhwinfo

Properties

BoardIndex, ChassisIndex, LogicalAddress, Name, Port, PrimaryAddress, RsrcName, SecondaryAddress, Status, Type

udp

Property Reference