visadev Properties

Access VISA resource properties

Since R2021a

Configure your VISA resource and its communication settings using its properties. After you create a visadev object, you can use dot notation to read and set properties.

Object Creation Properties

ResourceName — VISA resource name

string scalar

VISA resource name, returned as a string scalar. Identify the resource name of the device you want to connect to using the information returned by visadevlist. This property can be set only at object creation.

Each type of VISA interface has a different format, described in the following table. The VISA resource name format and its parameters are defined by the VISA standard specifications. Replace the italicized text with values for the specified parameters. The parameters in brackets are optional.

Interface	Resource Name
TCP/IP (using VXI-11 or HiSLIP)	TCPIP[board]::remote_host[::lan_device_name]::INSTR
TCP/IP Socket	TCPIP[board]::remote_host::port::SOCKET
USB	USB[board]::vendor_ID::product_ID::serial_number[::interface_number]::INSTR
GPIB	GPIB[board]::primary_address[::secondary_address]::INSTR
Serial	ASRL[port_number]::INSTR
VXI	VXI[chassis]::VXI_logical_address::INSTR
PXI	PXI[bus]::device[::function][::INSTR] PXI[bus]::CHASSISchassis::SLOTslot[::FUNCfunction][::INSTR]

The resource name parameters are described as follows. Each parameter corresponds to one of the visadev properties.

Interface	Parameter	Description
All	board	Board index (default value of 0)
TCP/IP (using VXI-11 or HiSLIP) and TCP/IP Socket	remote_host	Remote host name or IP address of the instrument
	lan_device_name	Local Area Network (LAN) device name (default value of inst0)
	port	Remote host port for TCP/IP socket
USB	vendor_ID	Manufacturer ID of the USB instrument
	product_ID	Model code for the USB instrument
	serial_number	Index of the instrument on the USB hub
	interface_number	USB interface
GPIB	primary_address	Primary address of the GPIB instrument
	secondary_address	Secondary address of the GPIB instrument (default value of 0)
Serial	port_number	Serial port number (default value of 1)
VXI and PXI	chassis	VXI or PXI chassis index (default value of 0 for VXI)
	VXI_logical_address	Logical address of the VXI instrument
	bus	PCI bus number
	device	PCI device number
	function	PCI function number (default value of 0)
	slot	Slot number

Example: gpibdev = visadev("GPIB0::5::INSTR") connects to the GPIB device specified by the VISA resource name GPIB0::5::INSTR.

Data Types: char | string

Alias — VISA alias associated with resource

string scalar

VISA alias associated with resource, returned as a string scalar. Identify the alias of the device you want to connect to using the information returned by visadevlist. The alias is defined in your VISA vendor's configuration utility software. This property can be set only at object creation.

Example: serialdev = visadev("COM4") connects to the serial device specified by the VISA resource alias COM4.

Data Types: char | string

Type — Type of VISA resource

gpib | pxi | serial | socket | tcpip | usb | vxi

This property is read-only.

Type of VISA resource, returned as one of the supported VISA interfaces. Some properties and object functions are specific to an interface type.

Example: v.Type returns the type of VISA resource.

Vendor — Instrument manufacturer

string scalar

This property is read-only.

Instrument manufacturer, returned as a character vector or string scalar. This property is empty if the VISA interface type does not provide information about the manufacturer.

Example: v.Vendor returns the name of the instrument manufacturer.

Data Types: string

Model — Instrument model

string scalar

This property is read-only.

Instrument model, returned as a character vector or string scalar. This property is empty if the VISA interface type does not provide information about the model.

Example: v.Model returns the name of the instrument model.

Data Types: string

SerialNumber — Unique serial number associated with instrument

string scalar

This property is read-only.

Unique serial number associated with instrument, returned as a character vector or string scalar. This property is empty if the VISA interface type does not provide information about the serial number.

Example: v.SerialNumber returns the instrument serial number.

Data Types: string

Tag — Label for identifying connection

"" (default) | string

Since R2024a

Label for identifying connection, specified as a string. Use Tag to apply a label to a connection that you can use later to access the connection using visadevfind. Doing so can be useful when you open a connection in one function and use a different function to perform operations on the connection. It is also useful for locating and accessing connections in app callbacks.

Example: v.Tag = "Scope" sets the label to "Scope".

Data Types: string

Read and Write Properties

ByteOrder — Sequential order of bytes

"little-endian" (default) | "big-endian"

Sequential order in which bytes are arranged into larger numerical values, returned as "little-endian" or "big-endian".

Example: v.ByteOrder = "big-endian" sets the byte order to big-endian.

Data Types: char | string

Timeout — Allowed time to complete operations

10 (default) | numeric

Allowed time in seconds to complete read and write operations, returned as a numeric value.

Example: v.Timeout = 20 sets the timeout period to 20 seconds.

Data Types: double

Terminator — Terminator character for data

"LF" (default) | "CR" | "CR/LF" | 0 to 255

Terminator character for reading and writing ASCII-terminated data, returned as "LF", "CR", "CR/LF", or a number from 0 to 255, inclusive. If the read and write terminators are different, Terminator is returned as a 1x2 cell array of these values. Set this property with the configureTerminator function.

Example: configureTerminator(v,"CR") sets both the read and write terminators to "CR".

Example: configureTerminator(v,"CR",10) sets the read terminator to "CR" and the write terminator to 10.

Data Types: double | char | string

NumBytesWritten — Total number of bytes written

0 (default) | numeric

This property is read-only.

Total number of bytes written, returned as a numeric value.

Example: v.NumBytesWritten returns the number of bytes written.

Data Types: double

Callback Properties

ErrorOccurredFcn — Callback function triggered by error event

function handle

Callback function triggered by an error event, returned as a function handle. An error event is generated when the connection to your VISA resource is interrupted or when an asynchronous read error occurs. This property is empty until you assign a function handle.

Example: v.ErrorOccurredFcn = @myErrorFcn

Data Types: function_handle

UserData — General purpose property for user data

any type

General purpose property for user data, returned as any MATLAB^® data type. For example, you can use this property to store data when an event is triggered from a callback function.

Example: v.UserData

VISA-TCP/IP

LANName — LAN device name

string scalar

This property is read-only.

LAN device name, returned as a string.

Example: v.LANName returns the LAN device name.

Data Types: string

InstrumentAddress — TCP/IP address of instrument

string scalar

This property is read-only.

TCP/IP address of instrument in dot-decimal notation, returned as a string.

Example: v.InstrumentAddress returns the IP address of the instrument.

Data Types: string

BoardIndex — Index number of network board associated with instrument

numeric

This property is read-only.

Index number of network board associated with instrument, returned as a positive integer value.

Example: v.BoardIndex returns the network board index number.

Data Types: double

VISA-Socket

IPAddress — TCP/IP address of socket

string scalar

This property is read-only.

TCP/IP address of socket in dot-decimal notation, returned as a string.

Example: v.IPAddress returns the IP address of the socket.

Data Types: string

Port — Port number for given TCP/IP address

string scalar

This property is read-only.

Port number for given TCP/IP address, returned as a string.

Example: v.Port returns the port number associated with the TCP/IP address.

Data Types: string

VISA-USB Properties

VendorID — Manufacturer ID number of device

string scalar

This property is read-only.

Manufacturer ID number of device (VID), returned as a string.

Example: v.VendorID returns the vendor ID.

Data Types: string

ProductID — Model code of device

string scalar

This property is read-only.

Model code of device (PID), returned as a string.

Example: v.ProductID returns the product ID.

Data Types: string

BoardIndex — USB board number

numeric

This property is read-only.

USB board number, returned as a positive integer value.

Example: v.BoardIndex returns the USB board number.

Data Types: double

InterfaceIndex — USB interface number

numeric

This property is read-only.

USB interface number, returned as a positive integer value.

Example: v.InterfaceIndex returns the USB interface number.

Data Types: double

VISA-GPIB Properties

BoardIndex — GPIB board index

numeric

This property is read-only.

GPIB board index, returned as a positive integer value.

Example: v.BoardIndex returns the GPIB board index.

Data Types: double

PrimaryAddress — GPIB primary address

numeric

This property is read-only.

GPIB primary address associated with instrument, returned as an integer from 0 to 30, inclusive.

Example: v.PrimaryAddress returns the GPIB primary address.

Data Types: double

SecondaryAddress — GPIB secondary address

numeric

This property is read-only.

GPIB secondary address associated with instrument, returned as an integer from 0 to 30, inclusive.

Example: v.SecondaryAddress returns the GPIB secondary address.

Data Types: double

EOIMode — EOI Mode

"on" (default) | "off"

EOI mode, returned as on or off. This property specifies whether the EOI (end or identify) line is asserted at the end of a write operation.

Example: v.EOIMode = "off" does not assert an EOI line at the end of a write.

Data Types: char | string

VISA-Serial

Port — Serial communication port

string scalar

This property is read-only.

Serial communication port, returned as a string.

Example: v.Port returns the serial communication port.

Data Types: string

BaudRate — Communication speed

9600 (default) | double

Speed of serial communication in bits per second, returned as a positive integer.

Example: v.BaudRate = 14400 sets the baud rate to 14400.

Data Types: double

DataBits — Number of bits to represent one character of data

8 (default) | 7 | 6 | 5

Number of bits to represent one character of data, returned as 8, 7, 6, or 5.

Example: v.DataBits = 5 sets the number of data bits to 5 bits.

Data Types: double

StopBits — Pattern of bits that indicates the end of a character

1 (default) | 1.5 | 2

Pattern of bits that indicates the end of a character or of the whole transmission, returned as 1, 1.5, or 2. This property depends on the value of the DataBits property as follows.

Value of DataBits	Supported Values of StopBits
8, 7, or 6	1 and 2
5	1 and 1.5

Example: v.StopBits = 2 sets the number of stop bits to 2.

Data Types: double

Parity — Parity bit type

"none" (default) | "even" | "odd"

Parity bit type added to data transmitted by serial port, returned as "none", "even", or "odd". You can use this property to add a parity bit (also referred to as a check bit) to your data. Adding a parity bit to a string of binary code is a method of detecting errors in data transmission by ensuring that the total number of 1-bits is even or odd.

The value of the parity bit is determined by the number of 1s in a given set of bits and is set as follows.

Parity Bit Type	Parity Bit Value
	If number of 1s is even	If number of 1s is odd
none	No parity bit set	No parity bit set
even	0	1
odd	1	0

Example: v.Parity = "even" sets the parity bit type to even.

Data Types: char | string

FlowControl — Mode for managing data transmission rate

"none" (default) | "hardware" | "software"

Mode for managing data transmission rate, returned as "none", "hardware", or "software". Specify "none" to have no flow control, "hardware" to let your hardware determine the flow control, and "software" to let your software determine the flow control.

Example: v.FlowControl = "hardware" sets the flow control to hardware.

Data Types: char | string

VISA-VXI and VISA-PXI Properties

Bus — PCI bus number

numeric

This property is read-only.

PCI bus number for device, returned as a positive number. This property is only for VISA-PXI interface objects.

Example: v.Bus returns the device's PCI bus number.

Data Types: double

DeviceIndex — PXI device number

numeric

This property is read-only.

PXI device number, returned as a positive number. This property is only for VISA-PXI interface objects.

Example: v.DeviceIndex returns the PXI device number.

Data Types: double

FunctionIndex — PXI function number

numeric

This property is read-only.

PXI function number, returned as a positive number. This property is only for VISA-PXI interface objects.

Example: v.FunctionIndex returns the PXI function number.

Data Types: double

ChassisIndex — PXI or VXI chassis index number

numeric

This property is read-only.

PXI or VXI chassis index number, returned as a positive number.

Example: v.ChassisIndex returns the PXI or VXI chassis index number.

Data Types: double

LogicalAddress — VXI instrument logical address

numeric

This property is read-only.

VXI instrument logical address, returned as a positive number. This property is only for VISA-VXI interface objects.

Example: v.LogicalAddress returns the VXI instrument logical address.

Data Types: double

Slot — PXI or VXI instrument slot location

numeric

This property is read-only.

PXI or VXI instrument slot location, returned as a positive number.

Example: v.Slot returns the PXI or VXI instrument slot location.

Data Types: double

EOIMode — EOI Mode

"on" (default) | "off"

EOI mode, returned as on or off. This property specifies whether the EOI (end or identify) line is asserted at the end of a write operation.

Example: v.EOIMode = "off" does not assert an EOI line at the end of a write.

Data Types: char | string

Version History

Introduced in R2021a

R2024a: New Tag Property

Use the new Tag property to apply a label to a connection that you can use later to access the connection using visadevfind.

R2022a: visadev interface no longer supports callback functions

Callback functions are no longer supported for the visadev interface. The configureCallback function and the NumBytesAvailable, BytesAvailableFcnMode, BytesAvailableFcnCount, and BytesAvailableFcn properties and are no longer supported for visadev objects.