Function Reference

_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.

#include <Visa.au3>
_viSetAttribute($h_session, $i_attribute, $i_value)

Parameters

$h_session	A VISA descriptor (STRING) OR a VISA session handle (INTEGER). See the Remarks of the _viExecCommand for more info.
$i_attribute	The index of the attribute that must be changed. Attributes are defined in the VISA library. This AutoIt library only defines a CONSTANT for the TIMEOUT attribute ($VI_ATTR_TMO_VALUE) and for the Serial Interface attributes and values (see the remarks) but you can pass any other valid index (as an integer) if you want to.
$i_value	The value of the attribute. It must be an integer and the possible values depend on the attribute type and are defined in the VISA documentation.

Return Value

Success:	Returns 0
Failure:	Returns -1 if the VISA DLL could not be open or a NON ZERO value representing the VISA error code (see the VISA programmer's guide).

This function always sets @error to 1 in case of error.

Remarks

This is a list of the currently pre-defined attributes and values. Remember that you can use any other valid attribute/value by passing the corresponding integer index (as defined in the VISA programmer's guide) to this function.

* Attribute: $VI_ATTR_TMO_VALUE -> Set Timeout
* Values:
          A timeout in MILLISECONDS or
          $VI_TMO_IMMEDIATE (or 0) for "Return immediatly"
          VI_TMO_INFINITE (or "INF") for "No timeout"

* Attribute: $VI_ATTR_ASRL_BAUD
* Values:
          Any valid baudrate (9600, 115200, etc)

* Attribute: $VI_ATTR_ASRL_DATA_BITS
* Values:
          From 5 to 8

* Attribute: $VI_ATTR_ASRL_PARITY
* Values:
          $VI_ASRL_PAR_NONE
          $VI_ASRL_PAR_ODD
          $VI_ASRL_PAR_EVEN
          $VI_ASRL_PAR_MARK
          $VI_ASRL_PAR_SPACE

* Attribute: $VI_ATTR_ASRL_STOP_BITS
* Values:
          $VI_ASRL_STOP_ONE
          $VI_ASRL_STOP_ONE5
          $VI_ASRL_STOP_TWO

* Attribute: $VI_ATTR_ASRL_FLOW_CNTRL
* Values:
          $VI_ASRL_FLOW_NONE
          $VI_ASRL_FLOW_XON_XOFF
          $VI_ASRL_FLOW_RTS_CTS
          $VI_ASRL_FLOW_DTR_DSR

As for all the VISA functions the VISA libraries must be installed (you can check whether visa32.dll is in {WINDOWS}\system32).
You onlly need a GPIB card (such as a National Instruments NI PCI-GPIB card or an Agilent 82350B PCI High-Performance GPIB card) if you use the GPIB related functions.

* For a detailed description of the most common VISA DESCRIPTORS look at the Remarks of the help on the _viExecCommand function

Example

;- This assumes that you have instrument set to GPIB address 3.
; If you have an instrument in a different address change "GPIB::3::0" to the
; corresponding descriptor. Do the same for the call to _viOpen
; It shows how to use the _viSetAttribute. In this example we use _viSetAttribute
; instead of _viSetTimeout to set the GPIB timeout of a _viExecCommand operation.

#include <Visa.au3>

Dim $h_session = 0

; Query the ID of the instrument in GPIB address 3
MsgBox(0,"Step 1","Simple GPIB query with explicit TIMEOUT set")
Dim $s_answer = _viExecCommand("GPIB::3::0","*IDN?",10000) ; 10 secs timeout
MsgBox(0,"GPIB QUERY result",$s_answer) ; Show the answer

; This is the same as using the _viSetAttribute function first:
MsgBox(0,"Step 2","_vOpen + timeout using _viSetAttribute + GPIB query")
Dim $h_instr = _viOpen(3)
; NOTE - This is the same as: _viSetTimeout($h_instr, 10000)
_viSetAttribute($h_instr, $VI_ATTR_TMO_VALUE, 10000) ; 10000 ms = 10 secs

$s_answer = _viExecCommand($h_instr,"*IDN?") ; No need to set the timeout now
MsgBox(0,"GPIB QUERY result",$s_answer) ; Show the answer

MsgBox(0,"Step 3","Close the Instrument connection using _viClose")
_viClose($h_instr) ; Close the instrument connection