Automatic VB6 to pic serial connection

[arniepj]

The attached project files demonstrate how to make an automatic serial connection between a VB6 interface and a pic. This relieves the user from having to know what port the pic is connected to and then manually connect . This is very useful when using a USB to serial converter, as the virtual port numbers can be from com 5 on up and change depending on the USB port being used. The VB6 application functions as follows: As the application loads, the program attempts to open port 1.If this fails, the program errors, leaves the routine, increments the port number and attempts to open the next port. If the opening is successful, the program transmits a character that the pic will recognize, and in turn the pic will begin sending data. The VB6 program will wait for a period of time for data to arrive, if successful the application will finish loading and data will be displayed. If unsuccessful, the program will try all the ports until exhausted, displaying no connection. When the application is shut down, the program transmits a character that the pic will recognize, and in turn the pic will stop sending data. The pic used was a 16F873A. At the very least its another example for serial communication between a pc and a pic. Some of the code was found on VBnet.com and modified.

[Ioannis]

Hi Arnie,

nice example! Thanks for posting.

Ioannis

[T.Jackson]

Suggest using timegettime or gettickcount API's for the delay. This approach will ensure that it runs at the same speed on every machine. Plus, it will also make the process much more efficient, with no dead time - other processes can be processed in the background. A for next loop with an irritation of 10,000 is a big ask for poor'ol slow & obsolete VB6.

[Ioannis]

Hi Trent. How do you use the API's? I am really new at the VB things and appreciate an example if you can.

Thanks,
Ioannis

[mister_e]

The usual way is to call it in a module and use the function in your code.

Add a module to your project and past the following ones...

        Option Explicit

Private Declare Function GetTickCount Lib "kernel32" () As Long

Public Function GetTicks() As Long
        GetTicks = GetTickCount()
        End Function

In your Form(s), you just need to call it..

        Option Explicit
        Dim TickValue As Long

Private Sub Form_Load()
        Command1.Caption = "Start"
        Command2.Caption = "Stop"
        Text1.Text = ""
        End Sub

Private Sub Command1_Click()
        TickValue = GetTicks
        End Sub

Private Sub Command2_Click()
        TickValue = GetTicks - TickValue
        Text1.Text = TickValue
        End Sub

HTH

[dhouston]

Windows supports 256 COM ports. While few PCs will have a large number of ports, with the proliferation of USB/serial adapters and ethernet/serial adapters, there may be several ports and they usually do not use contiguous numbers. Testing all 256 possibilities can be quite time consuming. I think it's best to first enumerate the ports, eliminate those that are infrared, modems, etc. and then test the remainder. This is much faster and more reliable. Do a Google search using "VB enumerate COM ports" and you will find lots of example code. Many examples check the registry but this is not an infallible method as users can edit the registry.

Here's an example written in PureBasic which uses the Windows API function EnumPorts. The backslash is PB's equivalent to VB's dot for referencing structure members (VB Type).

;--------------------------------------------------------
;
; SerialPorts.pbi
;
;--------------------------------------------------------

Structure API_PORT_INFO_2
  PortName.s
  MonitorName.s
  Description.s
  PortType.l
  Reserved.l
EndStructure

Global NewList Portinfos.API_PORT_INFO_2()
Global ports.s
Global NumPorts.l

Procedure.l GetAvailablePorts(ServerName.s="")
  Protected res.l, pcbNeeded.l,pcReturned .l,i.l,ret.l
  Protected *TempBuff,*pName,*strPortinfos.PORT_INFO_2
 
  If ServerName=""
    *pName=0
  Else
    *pName=@ServerName
  EndIf
  
  ;Get the number of bytes needed To contain the Data returned by the API call
  ret = EnumPorts_(*pName, 2, 0, 0, @pcbNeeded, @pcReturned)
  If pcbNeeded
    *TempBuff = AllocateMemory(pcbNeeded) ; Allocate the Buffer
    ret = EnumPorts_(*pName, 2, *TempBuff, pcbNeeded, @pcbNeeded, @pcReturned)
    If ret
      For i = 0 To pcReturned - 1
        ;set structure over the memory area
        *strPortinfos.PORT_INFO_2=*TempBuff+(i*SizeOf(PORT_INFO_2))
        AddElement(Portinfos())
        Portinfos()\PortName=PeekS(*strPortinfos\pPortName)
        Portinfos()\MonitorName=PeekS(*strPortinfos\pMonitorName)
        Portinfos()\Description=PeekS(*strPortinfos\pDescription)
        Portinfos()\PortType=*strPortinfos\fPortType
        If Not FindString(LCase(Portinfos()\Description),"infrared",1)
          If Not FindString(LCase(Portinfos()\Description),"modem",1)
            If Not FindString(ports,Portinfos()\PortName,1)
              If Left(Portinfos()\PortName,3)="COM" And FindString(Portinfos()\Description," Port",1)
                ;test each here by trying to open it 
                ports+Portinfos()\PortName
                numPorts+1
              EndIf  
            EndIf
          EndIf
        EndIf
      Next
    EndIf
    ;Free the Heap Space allocated for the Buffer
    If *TempBuff
      FreeMemory(*TempBuff)
    EndIf
  EndIf
 
  ProcedureReturn pcReturned
EndProcedure

Here's a link to a VB example. http://vbnet.mvps.org/index.html?cod.../enumports.htm

EnumPorts returns all of the printer ports on the PC. The COM ports are a subset of the printer ports.

[mister_e]

Yup, that's one method, i already did it but, using CreateFile.. but some says it doesn't work with Me/2000

However, there's no good reason to stick with VB6. All the above is 90% standard in .NET... the problem is just to move on .NET syntax