vb串口通信的疑难杂症!!!在线等，急急急急！！！
下面是我用ＶＢ做的串口通信部分的接收代码，由于几天找不到问题出现在哪里，希望好心人帮忙看看怎么回事，谢谢！Option Explicit
Dim strbuff As String
Dim inbte() As Byte
Dim outdata As Variant
Dim n As Integer
Dim indata As String
Dim n1 As Integer
Dim dd As String
Private Sub MSComm1_OnComm() '接收事件
Dim I As Integer
Select Case MSComm1.CommEvent
Case 2
strbuff = MSComm1.Input
inbte() = strbuff
For I = 0 To UBound(inbte)
indata = indata & Right("0" & Hex(inbte(I)), 2)
Next I
If Mid(indata, 1, 4) = "5A79" Then
indata = ""
Timer1.Enabled = False
Timer2.Enabled = True
ElseIf dd = "AA" And Mid(indata, 1, 18) = "358220100304050607" Then
Shape1.FillColor = vbGreen
indata = ""
MsgBox "连机OK!"
Timer2.Enabled = False
Timer1.Enabled = True
n = 0
n1 = 0
Else
MsgBox "接收代码有误", , "错误"
indata = ""
n1 = 0
Timer2.Enabled = True
Timer1.Enabled = False
End If
通信协议:38400,n,8,1
以二进制接收
代码大致意思是:当单击联机命令按钮时,timer1打开发送请求通信命令0XAA,如果收到下位机发来的0X5A79,则timer1关闭timer2(发送联机命令)打开,如果收到0X358220100304050607,则indata清空tiner2关闭
问题是:下位机发送的358220100304050607,我只收到前面16位,提示接收代码有误,这是怎么回事啊,我接收缓冲区设置的是1024,
请大家帮忙看看!在线等,急急,QQ:479702007
--------------------编程问答-------------------- 建议你用串口调试器发送一下命令，看看接受是什么 --------------------编程问答-------------------- 从OnComm事件触发到数据被完整的接收是需要时间的，你的程序在触发OnComm事件的时候就把数据从缓冲区里读走了，但是这个时候数据可能还没有传输完成呢，所以你只能取到一部分咯！ --------------------编程问答-------------------- Option Explicit
Dim strbuff As String
Dim inbte() As Byte
Dim outdata As Variant
Dim n As Integer
Dim indata As String
Dim n1 As Integer
Dim dd As String
Private Sub MSComm1_OnComm() '接收事件
Dim I As Integer
Select Case MSComm1.CommEvent
Case 2
strbuff = MSComm1.Input
inbte() = strbuff
For I = 0 To UBound(inbte)
indata = indata & Right("0" & Hex(inbte(I)), 2)
Next I
If Mid(indata, 1, 4) = "5A79" Then
indata = ""
Timer1.Enabled = False
MSComm1.RThreshold = 9 '***************************************
Timer2.Enabled = True
ElseIf dd = "AA" And Mid(indata, 1, 18) = "358220100304050607" Then
Shape1.FillColor = vbGreen
indata = ""
MsgBox "连机OK!"
Timer2.Enabled = False
Timer1.Enabled = True
n = 0
n1 = 0
Else
MsgBox "接收代码有误", , "错误"
indata = ""
n1 = 0
Timer2.Enabled = True
Timer1.Enabled = False
End If
--------------------编程问答-------------------- 不懂，路过 --------------------编程问答-------------------- 还是建议楼主先用串口调试器调试一下
我的资源中有一个串口调试器（附代码），你可以下载下来，单步调试一下，看看会有什么情况，两相对比，问题就明了了。 --------------------编程问答--------------------
有同解。 --------------------编程问答-------------------- '-------------------------------------------------------------------------------------------------------------------------
'MSComm1.RThreshold预先设的是多少？16吗？
'其实，完全可以抛开MSComm1_OnComm()用自己定义的状态来写程序。比较繁琐，可靠性更高。
'我是凭感觉改的，indata在下一个MSComm1_OnComm() 不被清空,Timer2.Enabled =True在执行Timer2.time()时调用MSComm1_OnComm() 。
'-------------------------------------------------------------------------------------------------------------------------
Private Sub MSComm1_OnComm()
Dim I As Integer
Select Case MSComm1.CommEvent
Case 2 '收到 Rthreshold 个字符。该事件将持续产生直到用 Input 属性从接收缓冲区中删除数据。
strbuff = MSComm1.Input
inbte() = strbuff
For I = 0 To UBound(inbte)
indata = indata & Right("0" & Hex(inbte(I)), 2)
Next I
If Mid(indata, 1, 4) = "5A79" Then
indata = ""
Timer1.Enabled = False
Timer2.Enabled = True
ElseIf dd = "AA" Then
if len(indata)>18 and Mid(indata, 1, 18) = "358220100304050607" then
Shape1.FillColor = vbGreen
indata = ""
MsgBox "连机OK!"
Timer2.Enabled = False
Timer1.Enabled = True
n = 0
n1 = 0
elseif len(indata)<18 then
Timer2.Enabled =True '下一个循环继续接收字符。
MSComm1.RThreshold = 1 '为了接受准确，如果上次发了16个字符而下次只发2个字符MSComm1.RThreshold设置>2可能永远会报错。
else
MsgBox "接收代码有误", , "错误"
indata = ""
n1 = 0
Timer2.Enabled = True
Timer1.Enabled = False
exit sub
endif
Else
MsgBox "接收代码有误", , "错误"
indata = ""
n1 = 0
Timer2.Enabled = True
Timer1.Enabled = False
exit sub
End If
--------------------编程问答--------------------
我认为欠妥，1>MSComm1.RThreshold = 9这句加的位置有待商榷。2>如果下个循环只发2~3个字符，MSComm1_OnComm事件就不会发生。 --------------------编程问答-------------------- 串口的数据发送与TCP/IP 不同,不是分包的.当串口有数据到数,并不意味着所有的数据全部到达,所以这时你要就循环取数据,但这要求你的通信协议要完善,即使从中间拆开数据,也能将它们拼回.
补充：VB , 网络编程
