Option Explicit

Dim ary() As String
Dim buf As Variant
Dim buf1 As Variant
Dim i As Integer           '变量的声名

Private Sub Form_Load()
= 2
MSC.Settings = "1200,n,8,1"
MSC.InBufferCount = 0
MSC.InputLen = 9
MSC.RThreshold = 9
MSC.PortOpen = True
End Sub                            'mscomm的初始化

Private Sub Form_Unload(Cancel As Integer)
If MSC.PortOpen = True Then MSC.PortOpen = False
End Sub

Private Sub MSC_OnComm()
Select Case
       Case comEvReceive
       buf = MSC.Input
       ReDim ary(Len(buf) - 1)
       For i = 1 To Len(buf)
       ary(i - 1) = Mid(buf, i, 1)
       Next
       Do While ary(0) <> "="
       txtreceive.Text = " "
       buf = MSC.Input
       ReDim ary(Len(buf) - 1)
       For i = 1 To Len(buf)
       ary(i - 1) = Mid(buf, i, 1)
       Next
       Loop                                '判断第一个字节是否为“=”，不是就进行循环等待！
       For i = 0 To UBound(ary)
       buf1 = buf1 + ary(i)
       Next
       txtreceive.Text = buf1
       buf1 = ""
       Case comEvSend
End Select
End Sub
   如果msc.input字符串中的第一个字符为“=”号，就能运行成功！如果不是，我就用do while 语句进行循环等待，我运行了多次发现，如果第一个字符不是“=”时，就运行错误，
错误提示是：实时错误“9”，下标越界。 真的不知哪儿错了？请高手帮忙看看！