Interfacing the LPT port...

General
1

I have a small 3-line LCD display that is connected via an LPT port. Just curious, but has anybody ever worked with something similar via RB/Xojo… or even sent data directly to an LPT port via RB/Xojo or even Visual Basic (that could be adapted and moved over)?

2

I haven’t seen a computer with an LPT port in 10 years or so.

Maybe an LPT to USB adapter would allow you to accessing it using the Serial class?

3

Xojo has no facility for working with the LPT port. You can use declares, I believe. I think there were some in the WFS.

4

Aaron once wrote a post on his now defunct blog.
I dont think he incorporated that one into the book though.
Not sure if the example made it into the internet way back machine

5

Appreciate the feedback, gentlemen. I got a solution to work by writing the text to a temp text file, then using shell to run a DOS command such as “copy temp.txt lpt1:” which worked just fine.

6

Maybe this information can be useful: http://forums.realsoftware.com/viewtopic.php?f=1&t=36609&hilit=printer+port

And the archive link: http://web.archive.org/web/20090708071141/http://www.aaronballman.com/programming/REALbasic/InpOut32RB.php

7

If someone with a PC and some time to translate it from VB6 to Xojo and test it, using Win32 were something like this:


Const GENERIC_WRITE = &H40000000
Const GENERIC_READ = &H80000000
Const FILE_ATTRIBUTE_NORMAL = &H80
Const OPEN_EXISTING = 3
Const INVALID_HANDLE_VALUE= -1

Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long

Private Declare Function WriteFile Lib "kernel32" ( _
        ByVal hFile As Long, lpBuffer As Any, _
        ByVal nNumberOfBytesToWrite As Long, _
        lpNumberOfBytesWritten As Long, ByVal lpOverlapped As Long) As Long

Private Declare Function CreateFile Lib "kernel32" _
        Alias "CreateFileA" (ByVal lpFileName As String, _
        ByVal dwDesiredAccess As Long, ByVal dwShareMode As Long, _
        ByVal lpSecurityAttributes As Long,  _
        ByVal dwCreationDisposition As Long, _
        ByVal dwFlagsAndAttributes As Long, ByVal hTemplateFile As Long) _
        As Long


Sub SendDataToLPT1(s As String)
      Dim myHandle As Long
      Dim BytesSent As Long
      myHandle=CreateFile("LPT1", GENERIC_READ Or GENERIC_WRITE, 0, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0)
      WriteFile myHandle, s, len(s), BytesSent, 0
      CloseHandle myHandle
End Sub
8