Operations
- Updated2026-08-05
- 6 minute(s) read
These topics describe the VISA operations. The operation descriptions are listed in alphabetical order for easy reference. Each event description contains a brief Purpose statement below the title. You will then see the operation defined in both ANSI C and Visual Basic version 4 syntax, with the parameters set in boldface type. A list indicating the supported resource classes, such as GPIB, Serial, etc. is followed by a table that describes each parameter and indicates whether it is an input or output parameter (or both, in some cases). The Return Values section describes the completion and error codes, followed by a detailed Remarks section. The Related topics section directs you toward related operations, attributes, events, or resource descriptions. If you want to know specifically about attributes, events, and operations of the INSTR Resource, for example, you should navigate to the INSTR Resource topic.
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Group members
| Name | Description |
|---|---|
| viAssertIntrSignal | Asserts the specified interrupt or signal. |
| viAssertTrigger | Asserts software or hardware trigger. |
| viAssertUtilSignal | Asserts or deasserts the specified utility bus signal. |
| viBufRead | Reads data from device or interface through the use of a formatted I/O read buffer. |
| viBufWrite | Writes data to a formatted I/O write buffer synchronously. |
| viClear | Clears a device. |
| viClose | Closes the specified session, event, or find list. |
| viDisableEvent | Disables notification of the specified event type(s) via the specified mechanism(s). |
| viDiscardEvents | Discards event occurrences for specified event types and mechanisms in a session. |
| viEnableEvent | Enables notification of a specified event. |
| viFindNext | Returns the next resource from the list of resources found during a previous call to viFindRsrc(). |
| viFindRsrc | Queries a VISA system to locate the resources associated with a specified interface. |
| viFlush | Manually flushes the specified buffers associated with formatted I/O operations and/or serial communication. |
| viGetAttribute | Retrieves the state of an attribute. |
| viGpibCommand | Write GPIB command bytes on the bus. |
| viGpibControlATN | Specifies the state of the ATN line and the local active controller state. |
| viGpibControlREN | Controls the state of the GPIB Remote Enable (REN) interface line, and optionally the remote/local state of the device. |
| viGpibPassControl | Tell the GPIB device at the specified address to become controller in charge (CIC). |
| viGpibSendIFC | Pulse the interface clear line (IFC) for at least 100 microseconds. |
| viIn16 | Reads in a 16-bit value from the specified memory space and offset. |
| viIn16Ex | Reads in an 16-bit value from the specified memory space and offset. |
| viIn32 | Reads in a 32-bit value from the specified memory space and offset. |
| viIn32Ex | Reads in a 32-bit value from the specified memory space and offset. |
| viIn64 | Reads in a 64-bit value from the specified memory space and offset. |
| viIn64Ex | Reads in a 64-bit value from the specified memory space and offset. |
| viIn8 | Reads in an 8-bit value from the specified memory space and offset. |
| viIn8Ex | Reads in an 8-bit value from the specified memory space and offset. |
| viInstallHandler | Installs handlers for event callbacks. |
| viLock | Establishes an access mode to the specified resources. |
| viMapAddress | Maps the specified memory space into the process's address space. |
| viMapAddressEx | Maps the specified memory space into the process's address space. |
| viMapTrigger | Map the specified trigger source line to the specified destination line. |
| viMemAlloc | Allocates memory from a resource's memory region. |
| viMemAllocEx | Allocates memory from a resource's memory region. |
| viMemFree | Frees memory previously allocated using the viMemAlloc() operation. |
| viMemFreeEx | Frees memory previously allocated using the viMemAllocEx() operation. |
| viMove | Moves a block of data. |
| viMoveAsync | Moves a block of data asynchronously. |
| viMoveAsyncEx | Moves a block of data asynchronously. |
| viMoveEx | Moves a block of data. |
| viMoveIn16 | Moves a block of data from the specified address space and offset to local memory. |
| viMoveIn16Ex | Moves a block of data from the specified address space and offset to local memory. |
| viMoveIn32 | Moves a block of data from the specified address space and offset to local memory. |
| viMoveIn32Ex | Moves a block of data from the specified address space and offset to local memory. |
| viMoveIn64 | Moves a block of data from the specified address space and offset to local memory. |
| viMoveIn64Ex | Moves a block of data from the specified address space and offset to local memory. |
| viMoveIn8 | Moves a block of data from the specified address space and offset to local memory. |
| viMoveIn8Ex | Moves a block of data from the specified address space and offset to local memory. |
| viMoveOut16 | Moves a block of data from local memory to the specified address space and offset. |
| viMoveOut16Ex | Moves a block of data from local memory to the specified address space and offset. |
| viMoveOut32 | Moves a block of data from local memory to the specified address space and offset. |
| viMoveOut32Ex | Moves a block of data from local memory to the specified address space and offset. |
| viMoveOut64 | Moves a block of data from local memory to the specified address space and offset. |
| viMoveOut64Ex | Moves a block of data from local memory to the specified address space and offset. |
| viMoveOut8 | Moves a block of data from local memory to the specified address space and offset. |
| viMoveOut8Ex | Moves a block of data from local memory to the specified address space and offset. |
| viOpen | Opens a session to the specified resource. |
| viOpenDefaultRM | This function returns a session to the Default Resource Manager resource. |
| viOut16 | Writes a 16-bit value to the specified memory space and offset. |
| viOut16Ex | Writes a 16-bit value to the specified memory space and offset. |
| viOut32 | Writes a 32-bit value to the specified memory space and offset. |
| viOut32Ex | Writes a 32-bit value to the specified memory space and offset. |
| viOut64 | Writes a 64-bit value to the specified memory space and offset. |
| viOut64Ex | Writes a 64-bit value to the specified memory space and offset. |
| viOut8 | Writes an 8-bit value to the specified memory space and offset. |
| viOut8Ex | Writes an 8-bit value to the specified memory space and offset. |
| viParseRsrc | Parse a resource string to get the interface information. |
| viParseRsrcEx | Parse a resource string to get extended interface information. |
| viPeek16 | Reads a 16-bit value from the specified address. |
| viPeek32 | Reads a 32-bit value from the specified address. |
| viPeek64 | Reads a 64-bit value from the specified address. |
| viPeek8 | Reads an 8-bit value from the specified address. |
| viPoke16 | Writes a 16-bit value to the specified address. |
| viPoke32 | Writes a 32-bit value to the specified address. |
| viPoke64 | Writes a 64-bit value to the specified address. |
| viPoke8 | Writes an 8-bit value to the specified address. |
| viPrintf | Converts, formats, and sends the parameters (designated by ...) to the device as specified by the format string. |
| viQueryf | Performs a formatted write and read through a single call to an operation. |
| viRead | Reads data from device or interface synchronously. |
| viReadAsync | Reads data from device or interface asynchronously. |
| viReadSTB | Reads a status byte of the service request. |
| viReadToFile | Read data synchronously, and store the transferred data in a file. |
| viSPrintf | Converts, formats, and sends the parameters (designated by ...) to a user-specified buffer as specified by the format string. |
| viSScanf | Reads, converts, and formats data from a user-specified buffer using the format specifier. Stores the formatted data in the parameters (designated by ...). |
| viScanf | Reads, converts, and formats data using the format specifier. Stores the formatted data in the parameters (designated by ...). |
| viSetAttribute | Sets the state of an attribute. |
| viSetBuf | Sets the size for the formatted I/O and/or low-level I/O communication buffer(s). |
| viStatusDesc | Returns a user-readable description of the status code passed to the operation. |
| viTerminate | Requests a VISA session to terminate normal execution of an operation. |
| viUninstallHandler | Uninstalls handlers for events. |
| viUnlock | Relinquishes a lock for the specified resource. |
| viUnmapAddress | Unmaps memory space previously mapped by viMapAddress(). |
| viUnmapTrigger | Undo a previous map from the specified trigger source line to the specified destination line. |
| viUsbControlIn | Performs a USB control pipe transfer from the device. |
| viUsbControlOut | Performs a USB control pipe transfer to the device. |
| viVPrintf | Converts, formats, and sends the parameters designated by params to the device or interface as specified by the format string. |
| viVQueryf | Performs a formatted write and read through a single call to an operation. |
| viVSPrintf | Converts, formats, and sends the parameters designated by params to a user-specified buffer as specified by the format string. |
| viVSScanf | Reads, converts, and formats data from a user-specified buffer using the format specifier. Stores the formatted data in the parameters designated by params. |
| viVScanf | Reads, converts, and formats data using the format specifier. Stores the formatted data in the parameters designated by params. |
| viVxiCommandQuery | Sends the device a miscellaneous command or query and/or retrieves the response to a previous query. |
| viWaitOnEvent | Waits for an occurrence of the specified event for a given session. |
| viWrite | Writes data to device or interface synchronously. |
| viWriteAsync | Writes data to device or interface asynchronously. |
| viWriteFromFile | Take data from a file and write it out synchronously. |
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