Aug 24, 2012 Visual Basic Serial COM Port Tutorial-Part 1 download the source code.
This is actually a continuation of a post already started relative to serial communications. I have a legacy access 2000 database that has been in successful use for over 10 years. It uses a MSComm control to read data from a scale. Tupac greatest hits. After moving to access 2007 and windows 7 of course, the mscomm control no longer works. I found a control that is supposed to replace the mscomm control.
- Make sure that you use Hardware Flow control!! In some serial port. I advice you to write an Unmanaged code on Visual Basic 6 / VC++6 DLL/OCX and use the.
- Visual Basic for Applications Serial Port Software Example. Visual Basic is used for many control applications, from simple communications, to elaborate test.
Selecting Serial Port Visual Basic
After replacing the mscomm control with the new control, following the suppliers instructions to the letter, it works, but when I close one of the forms containing the newly added control, Access crashes. I have worked on a solution for days and had a lot of help from other forum participants.
I have sort of come to the conclusion, that I need to take another route. So, I found a suggestion from someone that I handle serial communications with API calls. Not being very familiar with this routine, I downloaded the following code and added it to a button on a form. I assume that I would need to add some code, i.e. 'intPortID = 1' somewhere to set that variable to com1. I did that as the first line after the 'Initialze Communications line.
However, when I compile it, it says 'Sub or function not defined' on the 'lngStatus = CommOpen(intPortID, 'COM' & CStr(intPortID), 'baud=9600 parity=N data=8 stop=1')' line. What am I doing wrong? Can someone help me put this together to read data from a serial port? I don't need to write, only read.
Dim intPortID As Integer ' Ex. 1, 2, 3, 4 for COM1 - COM4 Dim lngStatus As Long Dim strError As String Dim strData As String ' Initialize Communications lngStatus = CommOpen(intPortID, 'COM' & CStr(intPortID)'baud=9600 parity=N data=8 stop=1') If lngStatus 0 Then ' Handle error. LngStatus = CommGetError(strError) MsgBox 'COM Error: ' & strError End If ' Set modem control lines. LngStatus = CommSetLine(intPortID, LINERTS, True) lngStatus = CommSetLine(intPortID, LINEDTR, True) ' Write data to serial port.
LngSize = Len(strData) lngStatus = CommWrite(intPortID, strData) If lngStatus lngSize Then ' Handle error. End If ' Read maximum of 64 bytes from serial port. LngStatus = CommRead(intPortID, strData, 64) If lngStatus 0 Then ' Process data. ElseIf lngStatus. Bruce, Again, thanks for helping me out, we are close I think. I think I am getting close, but have one hurdle that I cannot seem to solve. I have the code below.
When I run it, and send the string 'ST,+00009.28 g' it never seems to get to the exit do line, therefore stays in an endless loop. The string appears on my form, but that is as far as I get. Private Sub ReadClick Me.DataRead = ' Me.DataReadParsed = ' Dim intPortID As Integer ' Ex. 1, 2, 3, 4 for COM1 - COM4 intPortID = 1 Dim lngStatus As Long Dim strError As String Dim strData As String Call CommClose(intPortID) ' Initialize Communications lngStatus = CommOpen(intPortID, 'COM' & CStr(intPortID), 'baud=2400 parity=E data=7 stop=1') If lngStatus 0 Then ' Handle error. LngStatus = CommGetError(strError) MsgBox 'COM Error: ' & strError End If ' Set modem control lines.
Ps/2 Port
LngStatus = CommSetLine(intPortID, LINERTS, True) lngStatus = CommSetLine(intPortID, LINEDTR, True) ' Write data to serial port. LngSize = Len(strData) lngStatus = CommWrite(intPortID, strData) If lngStatus lngSize Then ' Handle error. End If ' Read maximum of 64 bytes from serial port.
Do While Right(Me.DataRead, 1) 'g' lngStatus = CommRead(intPortID, strData, 64) If lngStatus 0 Then Me.DataRead = Me.DataRead & strData If InStr(1, 'g', strData) 0 Then Exit Do End If ElseIf lngStatus 0 Then Exit Do 'End If it works, but I only get part of the string. I.e 'ST,+0000' Any Help?