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Chapter 6 Application Programs
Excel 5.0 Example for Windows 3.1 and GPIB
137
6
GPIB bas Macro
Option Explicit
' - Declarations for VISA.DLL, additional declarations are usually in the
' directory c:\vxipnp\win\include in file visa.bas, also see the VISA manual
Declare Function viOpenDefaultRM Lib "VISA.DLL" Alias "#141" (sesn As Long) As Long
Declare Function viOpen Lib "VISA.DLL" Alias "#131" (ByVal sesn As Long, _
ByVal desc As String, ByVal mode As Long, ByVal TimeOut As Long, vi As Long) As Long
Declare Function viClose Lib "VISA.DLL" Alias "#132" (ByVal vi As Long) As Long
Declare Function viRead Lib "VISA.DLL" Alias "#256" (ByVal vi As Long, _
ByVal Buffer As String, ByVal Count As Long, retCount As Long) As Long
Declare Function viWrite Lib "VISA.DLL" Alias "#257" (ByVal vi As Long, _
ByVal Buffer As String, ByVal Count As Long, retCount As Long) As Long
' Error Codes and other global variables
Global Const VI_SUCCESS = &h0&
Global videfaultRM As Long ' resource manager id for VISA GPIB
Global vi As Long ' stores the session for VISA
Dim errorStatus As Long ' VTL error code
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' This routine requires the file VISA.dll. It typically resides under
' the directory c:\windows\system. This routine uses the VTL Library to
' send commands to an instrument. A description of these and additional
' VTL commands are contained in the Hewlett Packard Visa Transition
' Library book Agilent PN E2094-90002.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Function SendSCPI(SCPICmd As String) As String
' This function will send a SCPI command string to the
' GPIB port. If the command contains a question mark,
' the response is read, and returned.
Dim readbuf As String * 512 ' buffer used for returned string
Dim crlfpos As Integer ' location of CR's and LF's in readbuf
Dim cmdString As String ' command passed to instrument
Dim ReturnString As String ' string returned from instrument
Dim actual As Long ' number of characters send/returned
'Set up an error handler within this subroutine that will get
'called if an error occurs.
On Error GoTo VIerrorHandler
'Write the command to the instrument terminated by a linefeed.
cmdstring = SCPICmd & Chr$(10)
errorStatus = viWrite(vi, ByVal commandstr, Len(commandstr), actual)