Using MSComm 1

[cscs]

What I am trying to do is to dial a phone number and have the program determine if that number is "busy" or "ringing". I can get the program to dial the number with no problem but to this point I have had no luck in returning anything but the number that is sent to the modem and an "OK" response.

I am using VB6, on winXP, with an external US Robotics 56K modem (I have also checked the modem DIP switches - to make sure it is returing text responses).

Below I have posted the code to try and get this accomplished, but still have not gotten the "Connect" or "Busy" response I am after. Any help on what I am doing wrong or what I should look for would be greatly appreciated.

Thanks.
-----------------------------------------------------------
Example
-----------------------------------------------------------
Private Sub cmdDial_Click()
Const MAX_TRIES = 10000

Dim results, mynum As String
Dim num_tries As Long

'need to figure out how to compare times

mynum = PNum1.Text
Screen.MousePointer = vbHourglass
On Error GoTo Oops

' Try to give MSComm1 time to close.
If MSComm1.PortOpen = True Then MSComm1.PortOpen = False

' Read the entire buffer when Input is used.
MSComm1.InputLen = 0
MSComm1.InBufferCount = 0
buffer = ""

' 9600 baud, no parity, 8 data bits, 1 stop bit.
MSComm1.Settings = "9600,N,8,1"

' Open the comm port.
MSComm1.PortOpen = True

' Send the attention string to the modem.
'MSComm1.Output = "ATV1Q0" & Chr$(13)
MSComm1.Output = "ATV1X4" & Chr$(13)

Do
' Read the latest data from the serial port.
DoEvents
results = results & MSComm1.Input
num_tries = num_tries + 1
If num_tries > MAX_TRIES Then
MsgBox "Did not get OK response in " & _
MAX_TRIES & " tries"
Exit Do
End If
Loop Until InStr(results, "OK" & vbCrLf) > 0



' Dial the phone number.
MSComm1.Output = "ATDT " & mynum & ";" & vbCr


Do
DoEvents
buffer = buffer + MSComm1.Input

If InStr(buffer, "Connect") Then
Text3.Text = "Connected"
MSComm1.PortOpen = False
End If

If InStr(buffer, "Busy") Then
Text3.Text = "Busy"
MSComm1.PortOpen = False
End If

Loop

Oops:
MsgBox "Error " & Err.Number & vbCrLf & _
Err.Description, _
vbExclamation Or vbOKOnly, _
"Error"
Screen.MousePointer = vbDefault
Exit Sub

End Sub

 

[TheVampire]

buffer = buffer + MSComm1.Input
I don't use "+" to add strings together. I've seen this cause problems before. Use "&" instead.

You also might try inserting a

Debug.Print buffer

statement in your buffer read loop, to see what it's actually getting. It might not be matching your strings exactly.

HTH

Robert

 

[mjk9564]

That's funny I have the same question.