# Visa user defined functions Reference

Below is a complete list of the user defined functions available in AutoIt. Click on a user defined function name for a detailed description.

When using them you need to add a #include <Visa.au3>.

User Defined Function | Description
--- | ---
_viClose | Closes a VISA connection to an Instrument/Device
_viExecCommand | Send a Command/Query to an Instrument/Device through the VISA interface (GPIB / TCP)
_viFindGpib | Send a Command/Query to an Instrument/Device through the VISA interface (GPIB / TCP)
_viGpibBusReset | GPIB BUS "reset": Use this function when the GPIB BUS gets stuck for some reason. You might be lucky and resolve the problem by calling this function
_viGTL | Go To Local mode: Instruments that accept this command will exit the "Remote Control mode" and go to "Local mode". If the instrument is already in "Local mode" this is simply ignored. Normally, if an instrument does not support this command it will simply stay in the "Remote Control mode"
_viInteractiveControl | Interactive VISA control to test your SCPI commands
_viOpen | Opens a VISA connection to an Instrument/Device
_viSetAttribute | Set any VISA attribute This function, which is called by _viSetTimeout, can ALSO be used to set the other VISA specific attributes. Read the VISA documentation for more information and a list of VISA attributes and their corresponding values
_viSetTimeout | Sets the VISA timeout in MILISECONDS