Interface RS232 en VB6

Private Sub UserForm_Initialize()
  '**************************************
  'Initialisation Port COM1:
    MSComm1.CommPort = 1
    'Parametrage ligne COM: (a adapter pour vous)
    MSComm1.Settings = "4800,N,8,1"
    'Ouvre le port de communication.
    On Error Resume Next
    MSComm1.PortOpen = True
    ' Vide le tampon d'entrée.
    MSComm1.InBufferCount = 0
    ' pas d'interruption
    MSComm1.RThreshold = 0
  '**************************************
End Sub

Private Sub Timer1_Timer()
  Dim nval As Double
  
  'Stop le timer
  Timer1.Enabled = False
  'Vide le tampon d'entrée.
  MSComm1.InBufferCount = 0
  
  MSComm1.Output = "read?" & vbCrLf
  txtTemps.Text = j
  
    'Attente nombre de caracteres prevu: a paramettrer
    LongueurAttendue = 55
    Port = 0
    Call AttenteNombreCaracteres(LongueurAttendue, Port)
    If Port = 0 Then
      MsgBox "Probleme reception!!!"
      'relance le timer
      Timer1.Enabled = True
      Exit Sub
    End If
    
  tampon$ = MSComm1.Input
  txtMesure.Text = txtMesure.Text & tampon$ & vbCrLf
  n = tampon$
  If Option2.Value = True Then
    ' MsgBox M
    m1 = Mid(n, 1, 5)
    m2 = Mid(n, 18, 23)
    m2 = Mid(m2, 1, 4)
    m3 = Mid(n, 33, 35)
    m3 = Mid(m3, 2, 4)
    m4 = Mid(n, 50, 55)
    m4 = Mid(m4, 1, 4)
    c1.t3 = j
    c1.m1 = m1 'voie 102
    c1.m2 = m2 ' voie 103
    c1.m3 = m3 'voie 104
    c1.m4 = m4 'voie 105
    ta = Val(c1.m1) * 10 'voie 102: temperature ambiente
    Txta.Text = ta
    tb = Val(c1.m2) * 10 'voie 103: temperature de la boite
    Txtb.Text = tb
    tc = Val(c1.m3) * 10 'voie 104: temperature chaude
    Txtc.Text = tc
    tf = Val(c1.m4) * 10 'voie 105: temperature froide
    Txtf.Text = tf
  End If
  'relance le timer
  Timer1.Enabled = True
End Sub
    
    
'SubRoutine attente caractere avec tempo: a adapter
Sub AttenteNombreCaracteres(LongueurAttendue As Integer, Port As Integer)
  Dim TemPort As Single
  Port = 0
  TemPort = Timer
  Do While MSComm1.InBufferCount < LongueurAttendue And Timer - TemPort < 1.6: Loop
  If MSComm1.InBufferCount = LongueurAttendue Then Port = 1
End Sub