加油站串口服务器突然断开什么原因

加油站串口服务器突然断开是网络中断。根据查询相关公开资料显示，网络中断就会导致串口通讯时信息发到一半断了。这个属于硬件处理，CPU不需要干预的。也就是往DR写入了数据后，就是外设串口在负责了，CPU就等着串口发完就好了，此时不等，随即进入中断，也无问题。

如果有确定的接收字节长度,设置Rthreshold等于接收字节长度有利接收正确率提高.由于你的几个下位机返回数据包字节不等长,你可根据寻址命令发出前预先改变Rthreshold值来保证接收返回符合要求的字节长度.

不然你接收多少字节符合你改发下一寻址命令呢?程序代码处理难度较高.

实际下位机返回数据包可在其代码中补一定其它字节来达到等长,从而使接收代码变得简洁.

等长接收数据后可对接收处理清0来等待下次接收.

补充：

假如下位机的返回数据按地址号能确定接收字节长度，下列代码可实现接收不等长数据，仅供参考：

Private Sub MSComm1_OnComm()

On Error Resume Next

Dim BytReceived() As Byte

Dim strBuff As String

Dim strData As String

Dim i As Integer

Dim x As Integer

Select Case MSComm1.CommEvent

Case 2

MSComm1.InputLen = 0

strBuff = MSComm1.Input

BytReceived() = strBuff

For i = 0 To UBound(BytReceived)

If Len(Hex(BytReceived(i))) = 1 Then

strData = strData &"0" &Hex(BytReceived(i))

Else

strData = strData &Hex(BytReceived(i))

End If

Next

Text3 = Text3 + strData

If Left(strData, 2) = "00" And Len(strData) = 8 Then

Text1(0).Text = Left(strData, 8)

Call DataClear

ElseIf Left(strData, 2) = "01" And Len(strData) = 10 Then

Text1(1).Text = Left(strData, 10)

Call DataClear

End If

End Select

End Sub

Public Sub DataClear()

MSComm1.OutBufferCount = 0 '清空发送缓冲区

MSComm1.InBufferCount = 0

Text3 = ""

End Sub

Private Sub Form_Load()

MSComm1.CommPort = 1 'COM端口

MSComm1.Settings = "9600,n,8,1"

MSComm1.InputMode = comInputModeBinary '采用二进制传输

MSComm1.InBufferCount = 0 '清空接受缓冲区

MSComm1.OutBufferCount = 0 '清空传输缓冲区

'MSComm1.SThreshold = 1 '如果传输缓冲区完全空时产生MSComm事件

MSComm1.RThreshold = 1 '不产生MSComm事件

MSComm1.PortOpen = True

Text3 = "" '打开端口

End Sub

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