MScomm doesn't work on non-vb computer

Hello,

I developed a vb6 application using the MScomm control which works great, through the vb IDE and the compiled version. I plan on using this program on a few other computers that do not have VB installed so I used the package and deployment wizard to create the necessary CAB files, etc.

I installed the program on another computer (also Win XP) and the application works with the exception of the serial communications. I don't get any errors it just does not work.

The MScomm32.ocx is in the correct directory and I even registered it manually based on some things I came across searching on the internet.

The question is, why won't the MScomm control work on machines that don't have VB installed even when the ocx is there and registered?

Thanks in advance!

sure the machines have the same device on the same port? you can't hard code that, if you want it to work on other devices

The program loads the available COM ports and the user can select the COM port they want. I have verified the correct COM port by using hyperterminal so I know that is not the issue.

I've read there are a lot of reliability issues with MSComm so I decided to go the direct Win32 API route. I wrote a little test program that uses direct API calls to read/write to a serial port to see if that would work on the other computer....and it does not, despite working great on my other computer that has VB6 installed.

So now I'm not so sure it is an MSComm issue...

I don't have any issues connecting to serial devices on either computer using TeraTerm, HyperTerm, etc.

Thanks for the reply.

Might want to include the VB6 Runtime Update. Never had a problem with this, to test a modem:

Code:

---

' Select the right COM port in the Properties of the control!

Private Sub Command1_Click()
  MSComm1.PortOpen = True
  MSComm1.Output = "AT" & Chr$(13)
  Do
    DoEvents
  Loop Until MSComm1.InBufferCount > 1
  Text1.Text = MSComm1.Input
End Sub

---

Well you surely do not need VB installed to get the MSComm control to work. I have used this control in many projects and have had many customers use it under Win2K, XP Sp1,Sp2,Sp3, XP MCE, Vista and 7. The only issue I have saw to date was a USB com port adapter, can't remember the make but some of these have been know to have issues.

There are several things that may be an issue, port setting, baud rate, data bits, stop bits parity...

What do you mean when you say it doesn't work? Is it not sending anything? Not receiveing anything? sending/receiving garbage? How are you testing and what results are you getting?

Hi,
I have the same above problem, the computer send date through the serial port, but cant receive any thing.
Thank you.

How are you checking to see if anything is received?
What is your RThreshold set to?

RT=1
I'm using logic analyzer to check the send. Also I'm sending data using MCU and "supposing" the program doesn't receive any thing.

Ps. Thank you for the quick reply.
Regards

Again how are you checking to see if the program is receiving anything?
If you have not written code to process the data that is received then there is no way you would know if it was getting there or not unless you know that it is not being sent from the other side in which case the problem would be on that end.

Hi,
The PC program suppose reads data from a Microcontroller and plot the received data on the screen, also it supposed to present a progress bar on the screen.
Ill try to upload a segments from the program soon.

Hi,
This is the structure of the program, with all the necessary code segments:

Code:

---


'written by Jim Rowe

Option Explicit
Dim intSampleCounter As Integer:            'data array counter/pointer
Dim intCOMPort As Integer:                  'current COM port for USB sampler
Dim intGain As Integer:                    'current gain setting
Dim intResp As Integer:                    'response variable from dialog boxes
Dim strPrompt As String:                    'prompt string for dialog boxes etc
Dim strCrLf As String:                      'string for Cr & Lf
Dim strBaud As String:                      'current baud rate setting for COM port
Dim strSaveFileName As String:              'filename for saving a set of samples
Dim strSampleRateCode As String:            'sample rate code to send to Sampler
Dim strPrintFontName As String:            'user selected printer font
Dim bytSamples(0 To 8191) As Byte:          'array for storage of data samples

Private Sub Form_Load()
    Dim strFetchStrg As String
    Call ClearDataArray
    Call DisplayData
    strSaveFileName = ""
    strCrLf = Chr(13) + Chr(10)
    strSampleRateCode = "1":                'code for default sampling rate
    intCOMPort = 5:                        'default COM port setting for USB
    strBaud = "38400":                      'default baud rate
    intGain = 2000:                        'and gain setting
    On Error GoTo ErrorHandler
    Open "ECGSAMPL.cfg" For Input As #3:    'if there's a config file, open it
        Input #3, strFetchStrg:            'skip past header line
        Input #3, strFetchStrg:            'and date/time stamp line
        Input #3, strSaveFileName:          'get name of last data file used
        Input #3, intCOMPort:              'and last COM port used
        Input #3, strBaud:                  'and its baud setting
        Input #3, strSampleRateCode:        'and last sampling rate code
        Input #3, intGain:                  'and last gain settings
        Input #3, strPrintFontName:        'finally last printer font used
    Close #3
    lblPortDisplay.Caption = CStr(intCOMPort)
    Call ShowPortSettings
    With MSComm1:                          'now set up COM port control
        .CommPort = intCOMPort:            'set COM port number
        .RThreshold = 1:                    'set Rx threshold to 1 char
        .SThreshold = 2:                    'and Tx threshold to 2 chars
        .Handshaking = comNone:            'set for no handshaking
        .InBufferSize = 8192:              'set input buffer for 8192 samples
        .InputLen = 8192:                  '& getting 8192 bytes at a time
        .InputMode = comInputModeBinary:    'set for binary input
    End With
    Call ShowSampleRate
    Call ShowGainSetting
    Call DisplayData:                      'show blank display
    Exit Sub:                              'this is normal exit
   
ErrorHandler:
    Close #3:                              'no config file, or corrupted; so
    Call DisplayData:                      'show blank display only
End Sub

Private Sub mnu1000SamplesPerSec_Click()
  .
  .
  .
End Sub

Private Sub mnu2000SamplesPerSec_Click()
  .
  .
  .
End Sub

Private Sub mnu500SamplesPerSec_Click()
  .
  .
  .

End Sub

Private Sub mnuAbout_Click()
  .
  .
  .
End Sub

Private Sub mnuPrint_Click()
  .
  .
  .
End Sub

Private Sub mnuSet28800_Click()
  .
  .
  .
   
End Sub

Private Sub mnuSet38400_Click()
  .
  .
  .
End Sub

Private Sub mnuSet9600_Click()
  .
  .
  .

End Sub

Private Sub mnuSetComPort_Click()
    Dim strDefault As String, intPortEntry As Integer
    strPrompt = "Set virtual COM port to which USB Sampler is connected:"
    strPrompt = strPrompt + strCrLf + "1-15"
    strDefault = "5"
    intPortEntry = CInt(InputBox(strPrompt, "Set COM Port", strDefault))
    If intPortEntry < 1 Or intPortEntry > 15 Then Exit Sub
    intCOMPort = intPortEntry
    lblPortDisplay.Caption = CStr(intCOMPort)
    MSComm1.CommPort = intCOMPort
End Sub

Private Sub mnuExit_Click()
  .
  .
  .
End Sub

Private Sub cmdGoSample_Click()
    If MSComm1.PortOpen = False Then MSComm1.PortOpen = True: 'open port if nec
    MSComm1.Output = "C" + strSampleRateCode:  'send command string to sampler
    MSComm1.DTREnable = True:                  'then set DTR true
    intSampleCounter = 0:                      'reset data array pointer
    pbSampleProgress.Value = 0:                'reset progress bar
End Sub

Private Sub FileOpen_Click()
  .
  .
  .

End Sub

Public Sub ClearDataArray()
    For intSampleCounter = 0 To 8191
        bytSamples(intSampleCounter) = 128
    Next intSampleCounter
   
End Sub

Public Sub OpenDataFile()
  .
  .
  .
End Sub

Public Sub SaveData()
  .
  .
  .
End Sub

Private Sub mnuSave_Click()
  .
  .
  .

End Sub

Public Sub DisplayData()
    picDisplay.Cls
    Call ShowGraticule
    For intSampleCounter = 0 To 8191
        Call PlotSample
    Next intSampleCounter
   
End Sub

Public Sub ShowGraticule()
    Dim intLineCtr As Integer
    Dim intXval As Integer, intYval As Integer
    picDisplay.DrawWidth = 1:                      'now set line width to 1
  picDisplay.ForeColor = &H80C0FF:                  'set colour to light orange
    For intLineCtr = 1 To 81
        intXval = 600 + (intLineCtr * 100):            'draw light vert lines
        picDisplay.Line (intXval, 100)-(intXval, 6500)
    Next intLineCtr
      For intLineCtr = 0 To 24
        intYval = 228 + (intLineCtr * 256):            '& light horiz lines
        picDisplay.Line (600, intYval)-(8792, intYval)
    Next intLineCtr
    picDisplay.ForeColor = &H80FF&:                    'set colour to orange
    picDisplay.DrawWidth = 2:                      '& set line width to 2
    picDisplay.Line (600, 100)-(8792, 100):        'then draw main frame
    picDisplay.Line (8792, 100)-(8792, 6500)
    picDisplay.Line (8792, 6500)-(600, 6500)
    picDisplay.Line (600, 6500)-(600, 100)
    For intLineCtr = 1 To 8
        intXval = 600 + (intLineCtr * 1000):            'draw main vert lines
        picDisplay.Line (intXval, 100)-(intXval, 6575)
    Next intLineCtr
    For intLineCtr = 0 To 4
        intYval = 740 + (intLineCtr * 1280):            '& main horiz lines
        picDisplay.Line (525, intYval)-(8792, intYval)
    Next intLineCtr
 
    picDisplay.ForeColor = &HFFFFFF:                    'change colour to white
    picDisplay.FontSize = 10: picDisplay.FontBold = True    'then print legends
    picDisplay.CurrentX = 250: picDisplay.CurrentY = 3200
    picDisplay.Print "0"
    picDisplay.CurrentX = 200: picDisplay.CurrentY = 20
    picDisplay.Print "mV"
    picDisplay.CurrentX = 200: picDisplay.CurrentY = 6380
    picDisplay.Print "mV"
    picDisplay.FontBold = False
    If intGain = 2000 Then
        picDisplay.CurrentX = 100: picDisplay.CurrentY = 625
        picDisplay.Print "+1.0"
        picDisplay.CurrentX = 100: picDisplay.CurrentY = 1900
        picDisplay.Print "+0.5"
    Else
        picDisplay.CurrentX = 100: picDisplay.CurrentY = 625
        picDisplay.Print "+0.5"
        picDisplay.CurrentX = 20: picDisplay.CurrentY = 1900
        picDisplay.Print "+0.25"
    End If
    If intGain = 2000 Then
        picDisplay.CurrentX = 120: picDisplay.CurrentY = 5750
        picDisplay.Print "-1.0"
        picDisplay.CurrentX = 120: picDisplay.CurrentY = 4475
        picDisplay.Print "-0.5"
    Else
        picDisplay.CurrentX = 120: picDisplay.CurrentY = 5750
        picDisplay.Print "-0.5"
        picDisplay.CurrentX = 40: picDisplay.CurrentY = 4475
        picDisplay.Print "-0.25"
    End If
    picDisplay.CurrentX = 7050: picDisplay.CurrentY = 6850
    picDisplay.FontBold = True
    picDisplay.Print "SECONDS"
    picDisplay.FontBold = False
    Select Case strSampleRateCode
        Case "5"
            For intLineCtr = 0 To 16
                picDisplay.CurrentX = 550 + (intLineCtr * 498)
                picDisplay.CurrentY = 6580
                picDisplay.Print CStr(intLineCtr)
            Next intLineCtr
        Case "1"
            For intLineCtr = 0 To 8
                picDisplay.CurrentX = 550 + (intLineCtr * 999)
                picDisplay.CurrentY = 6580
                picDisplay.Print CStr(intLineCtr)
            Next intLineCtr
        Case "2"
            For intLineCtr = 0 To 4
                picDisplay.CurrentX = 550 + (intLineCtr * 2000)
                picDisplay.CurrentY = 6580
                picDisplay.Print CStr(intLineCtr)
            Next intLineCtr
    End Select
   
End Sub

Public Sub PlotSample()
    Dim intXvalue As Integer, intYvalue As Integer
    Dim bytData As Byte
    picDisplay.ForeColor = &HFF00&                  'set colour to green
    intXvalue = 600 + intSampleCounter:            'get X position
    bytData = bytSamples(intSampleCounter)
    intYvalue = 6500 - (bytData * 25):              'and Y position
    picDisplay.Circle (intXvalue, intYvalue), 1:    'then plot, as tiny circle
   
End Sub


Private Sub mnuSetHighGain_Click()
  .
  .
  .
End Sub

Private Sub mnuSetLowGain_Click()
  .
  .
  .
End Sub

Private Sub mnuSetPrintFont_Click()
  .
  .
  .
End Sub

Private Sub MSComm1_OnComm()
    Dim bytInput() As Byte
    Dim lngCharCtr As Long
    If MSComm1.CommEvent = comEvReceive Then            'make sure it's data coming
        pbSampleProgress.Max = 100:                    'if so, initialise prog bar
        pbSampleProgress.Visible = True:                '& make it visible
        MSComm1.InBufferCount = 0:                      'clear Rx buffer
        lngCharCtr = 1:                                'reset timing counter
        'now wait until all samples are in buffer
        Do While MSComm1.InBufferCount < 8160
            pbSampleProgress.Value = CInt(100 * (MSComm1.InBufferCount / 8192))
        Loop
        lngCharCtr = CLng(MSComm1.InBufferCount)
        bytInput() = MSComm1.Input:                    'now get data from Rx buffer
        MSComm1.PortOpen = False:                      'close port
        'now transfer from one array to the other
        For intSampleCounter = 0 To CInt(lngCharCtr - 1)
            bytSamples(intSampleCounter) = bytInput(intSampleCounter)
            pbSampleProgress.Value = CInt(100 * (intSampleCounter / 8192))
        Next intSampleCounter:                          'do all samples
        pbSampleProgress.Visible = False:              'finally hide progress bar
        Call DisplayData:                              'and display new data
    End If
End Sub

Public Sub ShowSampleRate()
  .
  .
  .
End Sub

Public Sub ShowPortSettings()
  .
  .
  .
End Sub

Public Sub ShowGainSetting()
  .
  .
  .
End Sub

Public Sub ShowErrorMsg()
  .
  .
  .
End Sub

---

Maybe hard coding the modem port isn't the best way to do that.

What modem? Can you explain Please?
This program reads a stream of data (8192 bytes) through a virtual serial port (USB to RS232 converter), and display the data as a graph on the screen.
Regards.

Have you set a breakpoint in the oncomm event to see if it is firing?

What happens when the code is ran?


btw this is not needed

Code:

---

strCrLf = Chr(13) + Chr(10)

---

there is already a constant for this

VBCRLF

No, I didint set any breakpoint. I need some debugging advice at this point.
I tried to convert the project to VB2008 using VS2008 to overcome what l think , is compatibility issue, but VB2008 returned lots of errors. Is it an MScomm issue? ...I dont know.

The first step would be to place a break point in the on comm event near the top and then run the code in the IDE and send it some data. It should hit the breakpoint and from there you can step through the code.
If you can not reproduce the problem on the PC where VB is installed then I would suggest adding some code to write to a log file and key points including various points in the oncomm event then inspect the log file to see what may be going on on the troublesome pc.


The code you have shown looks like once it gets the on comm event will not break out of the loop and actually receive any data until the buffer holds about 8k characters. This is a bit unusual and I am not sure exactly how that would work out when it is in a tight loop while data is coming in. setting the break point and stepping through the code should shed some light.

Definitely do not upgrade the project to VB.Net, If you want it in VB.Net then you should rewrite it in VB.Net and use the Serial Port Class rather than the MSComm control.

I have used the MScomm control in several VB6 projects and have not had any issues with getting it to work properly.

You won't get anything to work using the upgrade assistant. You have to read every comment, and then look at the samples to see how to do that in .Net (which is probably the wrong way to start it). Pick a language, and start from there. VS2012 is current