使用VB的MSCOMM控件，調試過程很不順。首先是將發送命令的代碼放在一個過程里，但一運行就提示MSComm1.Output屬性使用無效，但相同的代碼放在窗體的Load事件里就正常。再一個是沒有注意到這個設備的停止位是2位，所以串口控件設置成“9600,n,8,1”時一直沒有數據返回。另外，看到RS485轉RS232的轉換器的接收燈一直在閃，可是串口控件的OnComm事件就是沒有觸發。
以下是調試通過的部分代碼：
Private Sub TimerMod_Timer()
Dim Send(8) As Byte
Dim SendStr As Variant
Dim Receive() As Byte
Dim ReceiveStr As Variant
Send(0) = &H1
Send(1) = &H3
Send(2) = &H0
Send(3) = &H0
Send(4) = &H0
Send(5) = &H1
Send(6) = 132 'CRC16 High
Send(7) = 10 'CRC16 Lo
SendStr = Send
MSComm1.Output = SendStr
Do
'這里需要加入超時判斷
DoEvents
Loop Until MSComm1.InBufferCount >= 7
MSComm1.bbbbbLen = 0
ReceiveStr = MSComm1.bbbbb
Receive = ReceiveStr
Text1.Text = CStr(HexToDec(Hex$(Receive(3)) & Hex$(Receive(4))))
End Sub
Function HexToDec(str)
Dim nums_len As Integer
Dim i As Integer
Dim tmpstr As bbbbbb
Dim dummy, tmp As Integer
dummy = 0
nums_len = Len(str)
For i = 1 To nums_len
tmpstr = Mid(str, i, 1)
If IsNumeric(tmpstr) Then
tmp = CInt(tmpstr) * 16 * (16 ^ (nums_len - i - 1))
Else
If Asc(UCase(tmpstr)) < 65 Or Asc(UCase(tmpstr)) > 70 Then
HexToDec = -1
Exit Function
End If
tmp = (Asc(UCase(tmpstr)) - 55) * (16 ^ (nums_len - i))
End If
dummy = dummy + tmp
Next
HexToDec = dummy
End Function
：鞏經理
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：南京塞姆泵業有限公司
