LPT Communication

BlitzPlus Forums/BlitzPlus Programming/LPT Communication

Arem	(Posted 2005) [#1]

Is it possible to communicate with the LPT port via the stream=openstream("LPT1") method? If so, what would the default baud rate be, and how can it be changed. Also, should I create a byte that determines whether each pin is on or off?

Yeshu777

(Posted 2005) [#2]

Search PortIO DLL. Allows you to toggle pins via byte and so forth.

Beaker

(Posted 2005) [#3]

deja vu:
http://blitzbasic.com/Community/posts.php?topic=46477

Arem	(Posted 2005) [#4]

Unfortunately, this requires other software to be installed and running previously. I am a stickler for having nothing running in the background on my pc, so if there is any other way, it would be wonderful.

I have read that it is possible to open up communication with the serial port via file=openfile("COM1") but I was wondering if the same method works with LPT.

Arem	(Posted 2005) [#5]

Well, I finally decided to go ahead and try writing data to LPT. I wrote a few random bytes (while forgetting to unplug the printer) and it freaked. But it works! If there are ways to set the baud rate etc. that would be great. Otherwise, I'm done.

Arem	(Posted 2005) [#6]

Scratch that. It writes to the printer buffer, which made the printer freak. Back to square 1.

Seldon

(Posted 2005) [#7]

You can access LPT or COM ports with Win32 API. You need some userlibs definitions for Blitz. Look for samples on this forum and on MSDN.

Wayne

(Posted 2005) [#8]

Sorry this is for B3d, but it may be of help.

I posted some parallel port I/O stuff in the user libs. It's low level and should allow you to read and write status, control and data bit/bytes. I used it to control the position of Radio Control servos.

http://www.blitzbasic.com/codearcs/codearcs.php?code=1487

It's been awhile since I've done low level output to printer, and it varies with hardware. In general write data, send strobe, watch status for ack, send next character. Also keep in mind printers have commands ie HPGL.

If it's application printing your looking for I think Kanati had a blitz3d printing dll, there maybe others out there.

Summary, Most OS's will require you use a DLL to allow access to hardware ports ( thats the law ). There is a winapi for printing as well, here is some vb6 code as example. Also don't use the word baud with parallel communications because there is no UART with parallel printing and thus no control register to set a rate.
8)

      Option Explicit

      Private Type DOCINFO
          pDocName As String
          pOutputFile As String
          pDatatype As String
      End Type

      Private Declare Function ClosePrinter Lib "winspool.drv" (ByVal _
         hPrinter As Long) As Long
      Private Declare Function EndDocPrinter Lib "winspool.drv" (ByVal _
         hPrinter As Long) As Long
      Private Declare Function EndPagePrinter Lib "winspool.drv" (ByVal _
         hPrinter As Long) As Long
      Private Declare Function OpenPrinter Lib "winspool.drv" Alias _
         "OpenPrinterA" (ByVal pPrinterName As String, phPrinter As Long, _
          ByVal pDefault As Long) As Long
      Private Declare Function StartDocPrinter Lib "winspool.drv" Alias _
         "StartDocPrinterA" (ByVal hPrinter As Long, ByVal Level As Long, _
         pDocInfo As DOCINFO) As Long
      Private Declare Function StartPagePrinter Lib "winspool.drv" (ByVal _
         hPrinter As Long) As Long
      Private Declare Function WritePrinter Lib "winspool.drv" (ByVal _
         hPrinter As Long, pBuf As Any, ByVal cdBuf As Long,  _
         pcWritten As Long) As Long

      Private Sub Command1_Click()
          Dim lhPrinter As Long
          Dim lReturn As Long
          Dim lpcWritten As Long
          Dim lDoc As Long
          Dim sWrittenData As String
          Dim MyDocInfo As DOCINFO
          lReturn = OpenPrinter(Printer.DeviceName, lhPrinter, 0)
          If lReturn = 0 Then
              MsgBox "The Printer Name you typed wasn't recognized."
              Exit Sub
          End If
          MyDocInfo.pDocName = "AAAAAA"
          MyDocInfo.pOutputFile = vbNullString
          MyDocInfo.pDatatype = vbNullString
          lDoc = StartDocPrinter(lhPrinter, 1, MyDocInfo)
          Call StartPagePrinter(lhPrinter)
          sWrittenData = "How's that for Magic !!!!" & vbFormFeed
          lReturn = WritePrinter(lhPrinter, ByVal sWrittenData, _
             Len(sWrittenData), lpcWritten)
          lReturn = EndPagePrinter(lhPrinter)
          lReturn = EndDocPrinter(lhPrinter)
          lReturn = ClosePrinter(lhPrinter)
      End Sub