VBA MSComm troubles

[dbrother]

Hello,
I have a program in Access that uses VBA to capture data being sent over the serial port from a Cosmo Flow Test Machine. This determines the air pressure's leak rate escaping from a muffler.

I have written several programs that send data out serially, but I am new to "listening" to receive the data.

I can setup an instance of HyperTerminal, provided the settings used in the given manual for the device and successfully retreive data results. When using the same settings in my VBA code, I never get any data; none. The data coming from HyperTerminal seems to be 'stream' based rather than packet, thus I used the code to keep adding the characters to the end until it finishes the loop.

Here's the code:

 
Private Sub cmdHHP_Click()
 
Dim strLeakRate As String
Dim strUprLmt As String
Dim strLwrLmt As String
Dim strChar As String
 
strUprLmt = 3.77
strLwrLmt = 0
 
lblStatus.Caption = "RETREIVING LEAK TEST DATA"
 
    MSComm0.CommPort = 1
    MSComm0.Settings = "1200,N,8,1"
    MSComm0.PortOpen = True
 
        Do Until strChar = ":"
            strChar = MSComm0.Input
            strLeakRate = strLeakRate & MSComm0.Input
        Loop
 
    MSComm0.PortOpen = False
 
lblStatus.Caption = "DATA RETREIVED"
 
    strLeakRate = Mid(strLeakRate, 6, 11)
    lblLeakRate.Caption = strLeakRate
 
 
 
        If strLeakRate > strUprLmt Then
            cmdFailed
            Exit Sub
        Else
            DoCmd.RunMacro "macHHP"
        End If
 
 lblStatus.Caption = "PRINTING LABEL"
 
'''''''''''
cmdReset
'''''''''''
 
End Sub
 
Public Sub cmdFailed()
 
 MsgBox "Test Failed. Please try the leak test at most 3 times for any one DPF.", vbCritical + vbOKOnly, "LEAK TEST FAILED"
End Sub
 
Public Sub cmdReset()
 
 strChar = ""
 strLeakRate = ""
 lblLeakRate.Caption = "-----"
 lblStatus.Caption = "READY"
 
End Sub
 
 

Looking at the form versus the code, it doesn't seem like it's preforming the first working line. I have a label that changes status when they click a 'start' button. As soon as the button is clicked, I would imiagine that the display message should change to 'RETREIVING LEAK TEST DATA'.

Another concern is that it doesn't seem like the port is actually ever opening. The code currently hangs in the loop waiting to receive the ":" char to denote the end of the string. I manually break the code and debug, then go back to the form to try again and I DO NOT receive a 'port already open' error as would be expected.

One last question... The manual claims that the end of the string is denoted by carriage return, <CR>. It lists what I would think to be the hexadecimal code for that as (0DH). How would I go about using that as the delimiter to signify the end of the string?

Any info anyone could share would be most appreciated.
Thanks in advance,
dbrother.

[Bum]

Hi dbrother,

you have a loop where you're looking for a colon. Are you sure a colon is supposed to come through? Why don't you try to say

code[vb]
strchar = ""
do until strChar <> ""

this way, if anything comes through you can see it.

also, the reason your program might seem like it's hanging up is b/c of this loop. You need to use DoEvents in the call to free up the interface so you can click a cancel button or something. Also, you need something in this loop to eventually get you out if nothing ever shows up. You know, like a counter.

Also, some of these call like

code[vb]
strChar = MSComm0.Input
strLeakRate = strLeakRate & MSComm0.Input

/code

could go inside your "ONComm" event for mscomm0

Also, are you sure the baud settings are correct? Most machines I've ever talked to used 9600 or more.

Hope this helps,

B