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Chapter 6 Application Programs
Example Program for Excel 97
142
'*********************************************************************************
' This routine send a SCPI command string to the GPIB port or RS-232 port.
' If the command contains a question mark, the response is read, and returned
'**********************************************************************************
Private Function SendSCPI(command As String) As string
Dim commandString As String ' Command passed to power supply
Dim ReturnString As String ' Store the string returned
Dim crlfpos As Integer ' Location of any nul’s in Read Buffer
Dim ReadBuffer As String * 512 ' Buffer used for returned string
Dim actual As Long ' Number of characters sent/returned
commandString = command & Chr$(10) ' The instrumented by linefeed
ErrorStatus = viWrite(power_supply, ByVal commandString, Len(commandString), _
actual)
CheckError "Can’t Write to Device"
If bGPIB = False Then
delay 0.5
End If
If InStr(commandString, "?") Then
ErrorStatus = viRead(power_supply, ByVal ReadBuffer, 512, actual)
CheckError "Can’t Read From Device"
ReturnString = ReadBuffer
crlfpos = InStr(ReturnString, Chr$(0))
If crlfpos Then
ReturnString = Left(ReturnString, crlfpos - 1)
End If
SendSCPI = ReturnString
End If
End Function
Private Function ClosePort()
ErrorStatus = viClose(power_supply)
ErrorStatus = viClose(defaultRM)
End Function
Private Function delay(delay_time As Single)
Dim Finish As Single
Finish = Timer + delay_time
Do
Loop Until Finish <= Timer
End Function
Private Function CheckError(ErrorMessage As String)
If ErrorStatus < VI_SUCCESS Then
Cells(5, 2) = ErrorMessage
ClosePort
End
End If
End Function
End of Program