Great! VB displays the number I sent. The program below:
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Private Sub Form_Load()
MSComm1.CommPort = 1
MSComm1.Settings = "1200,n,8,1"
MSComm1.RThreshold = 1
MSComm1.InputMode = comInputModeText
MSComm1.PortOpen = True
End Sub

Private Sub Form_Unload(cancel As Integer)
MSComm1.RTSEnable = False
MSComm1.PortOpen = False
End Sub

Private Sub MSComm1_OnComm()
Dim sData As String
If MSComm1.CommEvent = comEvReceive Then
Cls
sData = MSComm1.Input
Print Asc(sData)
End If
End Sub
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THANKS!

For the 51 side, I use a 8-bit dip switch to input a number and sent it to the PC. I just want to display the number. Why is it wrong to use the "MSComm1.InputMode = comInputModeBinary"?

Stanley