visadev

R2026b

Create connection to device using VISA

Description

A visadev object represents a connection to a device or instrument using the VISA interface. The following interface types are supported: TCP/IP (using VXI11 and HiSLIP), TCP/IP Socket, USB, GPIB, Serial, VXI, and PXI. Identify devices available to connect to using visadevlist. Then, connect to the device or instrument using visadev.

Creation

Syntax

deviceObj = visadev(resourceName)

deviceObj = visadev(resourceAlias)

deviceObj = visadev(resourceName,Identification=identificationCommand)

Description

deviceObj = visadev(resourceName) creates a connection to a device using its VISA resource name. Establish a connection using an installed VISA driver. If you have multiple VISA drivers installed, MATLAB^® uses the preferred VISA set in your VISA vendor's configuration utility software.

deviceObj = visadev(resourceAlias) creates a connection to a device using its VISA alias, if it has one. If the configuration utility does not yet recognize the device, you cannot connect using the alias and must use the resource name.

deviceObj = visadev(resourceName,Identification=identificationCommand) sends a custom identification command to query the device instead of the standard *IDN? query. Use this syntax for devices that use a proprietary identification command. (since R2026b)

Input Arguments

resourceName — VISA resource name

character vector | string scalar

VISA resource name, specified as a character vector or string scalar. You can identify the name of the resource you want to connect to using the information returned by visadevlist. This input sets the ResourceName property.

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

Data Types: char | string

resourceAlias — VISA alias associated with resource

character vector | string scalar

VISA alias associated with a resource, specified as a character vector or string scalar. Identify the alias of the resource you want to connect to using the information returned by visadevlist. You can use an alias only if an alias is assigned using the VISA vendor’s configuration utility software. This input sets the Alias property.

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

Data Types: char | string

identificationCommand — Identification command sent to device

"*IDN?" (default) (default) | string scalar | character vector

Identification command sent to the device during connection, specified as a string scalar or character vector. The device responds to this command, and the response populates the Vendor and Model properties.

Some instruments use a proprietary identification command instead of the IEEE 488.2 standard *IDN? query. Use this argument to specify the correct command for your device.

Specify an empty string ("") to skip identification entirely. When you skip identification, Vendor and Model properties are empty. The device object is still fully connected and you can perform read and write operations regardless of the identification setting.

When you specify a custom identification command, the function bypasses the cached resource information and queries the device directly.

Example: v = visadev("GPIB0::5::INSTR",Identification="ID?") connects to the device and uses the ID? command to identify it.

Data Types: char | string

Output Arguments

deviceObj — VISA device connection

visadev object

VISA device connection, returned as a visadev object. The object type depends on the interface of the connected device, such as GPIB, USB, TCPIP, or Serial.

Properties

See visadev Properties for a full list of properties.

Object Functions

read	Read data from VISA resource
readline	Read line of ASCII string data from VISA resource
readbinblock	Read one binblock of data from VISA resource
write	Write data to VISA resource
writeline	Write line of ASCII data to VISA resource
writebinblock	Write one binblock of data to VISA resource
writeread	Write command to VISA resource and read response
configureTerminator	Set terminator for ASCII string communication with VISA resource
flush	Clear buffers for communication with VISA resource
visastatus	Check status of VISA resource
visatrigger	Send trigger to GPIB or VXI instruments
setDTR	Set serial DTR pin
setRTS	Set serial RTS pin
getpinstatus	Get serial pin status

Examples

Connect to VISA Resource Using Name or Alias

Search for and establish a connection to your VISA resource.

Search for available VISA resources.

resourceList = visadevlist

resourceList =

  6×6 table

                        ResourceName                         Alias                  Vendor               Model       SerialNumber     Type 
         __________________________________________    _________________    ______________________    ___________    ____________    ______

    1    "USB0::0x0699::0x036A::CU010105::0::INSTR"    "NI_SCOPE_4CH"       "TEKTRONIX"               "TDS 2024B"    "CU010105"      usb   
    2    "TCPIP0::169.254.2.20::inst0::INSTR"          "Keysight_33210A"    "Agilent Technologies"    "33210A"       "MY57003523"    tcpip 
    3    "ASRL1::INSTR"                                "COM1"               ""                        ""             ""              serial
    4    "ASRL3::INSTR"                                "COM3"               ""                        ""             ""              serial
    5    "GPIB0::5::INSTR"                             "FGEN_2CH"           "Agilent Technologies"    "33522B"       "MY52800145"    gpib  
    6    "GPIB0::11::INSTR"                            "OSCOPE_2CH"         "TEKTRONIX"               "TDS 1002"     "0"             gpib  

Create a connection to the first resource over the VISA-USB interface using the resource name.

usbdev = visadev("USB0::0x0699::0x036A::CU010105::0::INSTR")

usbdev = 

  USB with properties:

         ResourceName: "USB0::0x0699::0x036A::CU010105::0::INSTR"
                Alias: "NI_SCOPE_4CH"
               Vendor: "TEKTRONIX"
                Model: "TDS 2024B"

  Show all properties, functions

Alternatively, you can connect to a device using its alias.

serialdev = visadev("COM1")

serialdev = 

  Serial with properties:

         ResourceName: "ASRL1::INSTR"
                Alias: "COM1"
                 Port: "ASRL1"
             BaudRate: 9600

  Show all properties, functions

Disconnect Single VISA Device Connection

When you use visadev in a script or at the MATLAB command line, the result is a connection represented by an object in the MATLAB workspace.

analyzerResource = "TCPIP0::K-N9040B-91124.dhcp.mathworks.com::inst0::INSTR";
V = visadev(analyzerResource);

V = 

  TCPIP with properties:

         ResourceName: "TCPIP0::K-N9040B-91124.dhcp.mathworks.com::inst0::INSTR"
                Alias: ""
               Vendor: "Keysight Technologies"
                Model: "N9040B"
              LANName: "inst0"
    InstrumentAddress: "172.31.173.155"
                  Tag: ""

When no references to the same connection exist in other variables, you can disconnect the device by clearing the workspace variable.

clear(V)

Use visadevfind to confirm that the connection is closed.

visadevfind

ans =

     []

Disconnect VISA Device Connections in Functions or App Callbacks

When you have a visadev connection that exists in the MATLAB workspace or is saved as a class property or app property, the visadev object might not be accessible in a different function or app callback. In this case, you can use visadevfind to find and delete the connection.

V = visadevfind

V = 

  TCPIP with properties:

         ResourceName: "TCPIP0::K-N9040B-91124.dhcp.mathworks.com::inst0::INSTR"
                Alias: ""
               Vendor: "Keysight Technologies"
                Model: "N9040B"
              LANName: "inst0"
    InstrumentAddress: "172.31.173.155"
                  Tag: "Analyzer"

To close this connection, delete V.

delete(V)

This command deletes the visadev object and disconnects the device. If you want to reconnect to the device, you must create a new connection with visadev.

After the deletion, calling visadevfind confirms that there are no existing connections.

visadevfind

ans =

     []

Note that the variable V is still present in the workspace, but it is now an invalid handle.

V

V = 

  handle to deleted TCPIP

The variable persists after deletion of the interface because visadev is a handle object. (For more information about this type of object, see Handle Object Behavior.) You can use clear to remove the invalid handle from the workspace.

clear V

Connect to Device with Custom Identification Command

Since R2026b

Connect to a device that uses a proprietary identification command instead of the standard *IDN? query.

Connect to a GPIB device using a custom identification command.

v = visadev("GPIB0::5::INSTR",Identification="ID?")

v =

  GPIB with properties:

         ResourceName: "GPIB0::5::INSTR"
                Alias: "FGEN_2CH"
               Vendor: "Agilent Technologies"
                Model: "33522B"

  Show all properties, functions

Alternatively, skip identification to connect without querying the device.

v = visadev("GPIB0::5::INSTR",Identification="")

v =

  GPIB with properties:

         ResourceName: "GPIB0::5::INSTR"
                Alias: ""
               Vendor: ""
                Model: ""

  Show all properties, functions

Version History

Introduced in R2021a

R2026b: Connect to devices that use a non-standard identification command

Use the Identification name-value argument to specify a custom identification command when connecting to devices that do not support the standard *IDN? query. Specify an empty string to skip identification entirely.

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 are no longer supported for visadev objects.