visadev

Create connection to device using VISA

Since R2021a

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

v = visadev(resourceName)

v = visadev(resourceAlias)

Description

v = 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.

v = 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.

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

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

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.