vb串口字节通信.txt

VB串口字节通信程序

1字节发送子程序：

Public Sub Sendbit(ByVal a As Integer) ；a为要发送的单字节数据
If a > 255 Then
a = 255
End If
If a < 0 Then
a = 0
End If
If MSComm1.PortOpen = False Then
MSComm1.PortOpen = True
End If
Dim mm(0 To 0) As Byte
mm(0) = a
MSComm1.OutBufferCount = 0
MSComm1.InBufferCount = 0
If MSComm1.PortOpen = True Then
MSComm1.Output = mm()
Else
MSComm1.PortOpen = True
MSComm1.Output = mm()
End If
End Sub

/////////////////////////////////////////////////////////

n字节接收子程序：

Private Sub MSComm1_OnComm()
Dim Buffer As Variant
Dim R(0 To n) As Integer   ;n为接收字节数
j = 0
Buffer = MSComm1.Input
For il = LBound(Buffer) To UBound(Buffer)
R(j) = Buffer(il)
j = j + 1
Next il
j = 0
Dim R0 As Integer
Dim R1 As Integer
Dim R2 As Integer
Dim R3 As Integer
  .
  .
  .
Dim Rn As Integer

R0 = R(0)   ;首字节
R1 = R(1) 
R2 = R(2) 
R3 = R(3)
  .
  .
  .
Rn = R(n)   ;末字节
End Sub

////////////////////////////////////////////////////

MSCOMM控件设置：

commport      :1~2
DTREnable     :true
EOFEnable     :false
Handshaking   :0-comNone
InBufferSize  :1024
InputLen      :0
InputMode     :1
NullDiscard   :false
OutBufferSize :512
ParityReplace :0
RThreshold    :1
RTSEnable     :false
Settings      :9600,n,8,1
SThreshold    :1