delphi 调用 vb做的dll，出现“access violation at address73474179 in module MSVBVM60.DLL
急！！ 请教！！我用delphi调用vb做的dll，最后出现这样的错误：“project project.exe raised exception class eaviolation with message "access violation at address73474179 in module MSVBVM60.DLL" read of address 00000076.”VB 中DLL的代码是：
Option Explicit
Dim io_mgr As VisaComLib.ResourceManager ' to be used for the resource manager
Dim DMM As VisaComLib.FormattedIO488 ' to create a formatted I/O reference
Dim connected As Boolean ' Sets flag to determine if instrument is connected or not
Sub RunProgram()
'"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
' This sub sets the 3458A to a pre-defined state, makes measurements, and
' returns the measurements.
'"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
If connected = False Then
If Not OpenPort Then
Exit Sub
End If
End If
' Setup the 3458A
Setup
' Call the sub that opens communication with instrument
' Make measurements and return readings
'GetReadings
End Sub
Sub Setup()
'"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
' This sub performs the instrument setup.
'"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
Dim Cmds As String
' Setup the 3458A
Cmds = "PRESET NORM;" ' Preset to the designated state (Normal)
Cmds = Cmds + "NRDGS 100,AUTO;" ' Set the number of readings pre trigger (4100 readings)
Cmds = Cmds + "TARM AUTO;" ' Setup the trigger
Cmds = Cmds + "TRIG HOLD;" ' Hold the trigge until triggered
Cmds = Cmds + "MEM FIFO;" ' Clear memory and set memory storage type
Cmds = Cmds + "MFORMAT DINT;" ' Set the memory storage format (double integer)
Cmds = Cmds + "OFORMAT ASCII;" ' Set the output format (ASCII)
Cmds = Cmds + "APER 1E-4;" ' Set the arperature time
' Set for the real time processing, if selected
Cmds = Cmds + "MATH STAT"
' Execute the commands
DMM.WriteString Cmds
' Check for errors
Check_Error "Setup"
End Sub
Function GetReadings() As Double
'"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
' This sub triggers the instrument and returns the readings from memory.
'"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
Dim rdcnt As Integer
Dim NumSamp As Integer
Dim StdDev As Double
Dim MeanVal As Double
Dim UpperVal As Double
Dim LowerVal As Double
SelectAddr_Click
RunProgram
' Trigger the 3458A
DMM.WriteString "TRIG SGL"
' Set sufficient timeout to make all measurements
DMM.IO.Timeout = 8000
With DMM
' Get number of readings taken
.WriteString "RMATH NSAMP"
NumSamp = .ReadNumber
' Get the standard deviation
.WriteString "RMATH SDEV"
StdDev = .ReadNumber
' Get the mean (avearage) value
.WriteString "RMATH MEAN"
MeanVal = .ReadNumber
' Get the upper (maximum) value
.WriteString "RMATH UPPER"
UpperVal = .ReadNumber
' Get the lower (minimum) value
.WriteString "RMATH LOWER"
LowerVal = .ReadNumber
End With
' Set timeout to a default value
DMM.IO.Timeout = 2000
' Check for errors
'Check_Error "GetReadings"
GetReadings = StdDev
End Function
Function OpenPort() As Boolean
'"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
' This function opens a port (the communication between the instrument and computer).
'"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
Dim addr As String ' to be used for the instrument address
Dim retval As String
' Exit if error occurs
' If port is open, close it
If connected Then
DMM.IO.Close
End If
' Set the resource manager session
Set io_mgr = New AgilentRMLib.SRMCls
' Create the VISA Com object
Set DMM = New VisaComLib.FormattedIO488
' Get the instrument address form the text box
addr = UCase$("GPIB::13")
' Set the VISA Com resource session
Set DMM.IO = io_mgr.Open(addr, True, True, "")
' Set timeout to 2 seconds
DMM.IO.Timeout = 2000
' Set the termination character to carriage return (i.e., 13);
' the 3458A uses this character
DMM.IO.TerminationCharacter = 13
' Set the flag to terminate when receiving a termination character
DMM.IO.TerminationCharacterEnabled = True
' Query instrument ID string
With DMM
.WriteString "ID?"
retval = .ReadString
End With
' Check if correct instrument is addressed
If InStr(retval, "3458A") = 0 Then
MsgBox "Wrong instrument addressed!"
' addrSelect.Text = "GPIB0::22"
' addrSelect.Refresh
connected = False
OpenPort = False
' Close the session
DMM.IO.Close
Exit Function
End If
' Reset the 3458A to it's power on state
DMM.WriteString "RESET"
' Check for errors
Check_Error "OpenPort"
connected = True
OpenPort = True
Exit Function
End Function
Sub ClosePort()
'"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
' This club closes the communication with the instrument.
'"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
If connected Then
' Close the port
DMM.IO.Close
End If
End Sub
Sub Check_Error(msg As String)
'"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
' Checks for syntax and other errors.
'"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
Dim ErrMsg As String * 80
' Check for error
With DMM
.WriteString "ERRSTR?"
ErrMsg = .ReadString
End With
' If error is found, show the error
End Sub
Private Sub SelectAddr_Click()
'"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
' Selects address and opens session
'"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
' Open port
If Not OpenPort Then
Exit Sub
Else
connected = True
End If
End Sub
我用DELPHI调用代码是：implementation
function GetReadings(StdDev:real):integer;stdcall;
external 'c:\aaa\ProjectOK.dll';
{$R *.dfm}
procedure TForm1.Button1Click(Sender: TObject);
var x:real;
begin
x:=GetReadings(StdDev);
edit1.text:= inttostr(StdDev);
//edit2.text:= inttostr(x);
//edit3.text:= inttostr(x);
//edit4.text:= inttostr(x);
end;
请教高手！！为什么每次调用DLL，点击delphi的button,就出现了前面提到的错误？？？ --------------------编程问答-------------------- 不懂，飘过~~~~~~~~~~~~~~~~~~~~~~~~~ --------------------编程问答-------------------- 高手现身啊！小弟实在着急啊！！ --------------------编程问答-------------------- 你要把VB写的DLL编译成win32 API的才行。
普通的DLL只有VB才能使用
补充：VB , API
