串口读取出来的数据怎样截取？

[aciom]

0 MW +0039.754 mm
0 MW -00001.16 mm
0 MW +0039.754 mm
0 MW +0039.754 mm
0 MW +003.754 mm
0 MW -0039.754 mm
0 MW +0039.754 mm
0 MW -0009.754 mm
0 MW +0039.754 mm
0 MW +0039.754 mm
0 MW +0039.754 mm
大家好 ，上面是串口发送出来的数据，每次一行，前面的0MW是站号，后面测量长度和单位，现在我想只要截取长度数据该如何写呢？
下面是oncomm事件的代码，谢谢大家指点。

Private Sub MSComm2_OnComm()
    Dim t1 As Long, com_String As String
    Static i As Integer
    t1 = Timer
    
    Sleep 100
    Select Case MSComm2.CommEvent
            Case comEvReceive '收到 RThreshold定义的字符数1字节
            MSComm2.RThreshold = 0
        Do
            DoEvents
        Loop While Timer - t1 < 0.6 '延时时间
        com_String = MSComm2.Input
        MSComm2.RThreshold = 1
        i = i + 1: If i > 255 Then i = 1
        Cells(actiCell + 1, actiColumn) = com_String
       ' Cells(actiCell + 1, 0).Value = com_String
        
        'Selection.Offset(0, 1).Select
        'Application .Cells(3, i).Value = com_String
    End Select
'ActiveWorkbook.SaveAs Filename:="C:\d1.xls"
End Sub

[pipi20151001]

上次写过一个与你类似的功能，只是数据格式与你不一样。分离字符串

[Tiger_Zhao]

    '模拟一次测试数据'
    com_String = "0 MW +0039.754 mm"
    '下面是提取方式'
    Dim a() As String
    a = Split(com_String, " ")
    If UBound(a) >= 2 Then
        Debug.Print "长度=" & a(2)
    End If

输出

长度=+0039.754