hi
thanks
若是一台 vista 不行那還可能是巧合，那如果是3台都一樣的情形咧？這還是巧合嗎？
xp 的環境下，ni-visa 允許已被使用中的 session可被另一支程式額外再開一個新的 session 來連接！
vista 的環境下， ni-visa 不允許已被使用中的 session可被另一支程式額外再開一個新的 session 來連接！
真的很怪！底下是我用 VB 6.0 改寫 NI-VISA 所附的程式，這程式我同時開啟兩個來運作，結果是VISTA下不允許另一個程式來連接。
Private Declare Function viGetAttrString Lib "VISA32.DLL" Alias "#133" (ByVal vi As ViSession, ByVal attrName As ViAttr, ByVal strValue As Any) As ViStatus
Sub Main()
Const MAX_CNT = 200
Dim fList As ViFindList
Dim status As ViStatus
Dim sesn As ViSession, dfltRM As ViSession
Dim buffer As String * MAX_CNT, Desc As String * 256
Dim nList As Long, retCount As Long
Dim rsrcName As String * VI_FIND_BUFLEN, instrDesc As String * VI_FIND_BUFLEN
status = viOpenDefaultRM(dfltRM)
If (status < VI_SUCCESS) Then
Rem Error initializing VISA ... exiting
Exit Sub
End If
status = viFindRsrc(dfltRM, "USB?*INSTR", fList, nList, rsrcName)
If (status < VI_SUCCESS) Then
status = viStatusDesc(dfltRM, status, Desc)
MsgBox "Error : " & Desc, vbOKOnly
viClose (dfltRM)
Exit Sub
End If
status = viOpen(dfltRM, rsrcName, VI_NULL, VI_NULL, sesn)
If (status < VI_SUCCESS) Then
status = viStatusDesc(dfltRM, status, Desc)
MsgBox "Could not open resource ;" & rsrcName, vbOKOnly, "Status"
MsgBox Desc, vbOKOnly
Else
status = viGetAttrString(sesn, VI_ATTR_INTF_INST_NAME, instrDesc)
MsgBox "Resource :" & Trim(rsrcName), vbOKOnly
End If
instrDesc = ""
status = viWrite(sesn, "read?", 5, retCount)
status = viRead(sesn, buffer, MAX_CNT, retCount)
If status < 0 Then
status = viStatusDesc(sesn, status, Desc)
MsgBox "Error : " & Desc, vbOKOnly
Else
MsgBox "The Value : " & buffer, vbOKOnly
End If
buffer = ""
viClear (sesn)
viGpibControlREN sesn, VI_GPIB_REN_DEASSERT_GTL
stat = viClose(fList)
stat = viClose(dfltRM)
End Sub
