"Stu Lock" <n***@cergis.com> wrote in message
news:%23%23stD5QpGHA.4208@TK2MSFTNGP04.phx.gbl...
> Hi,
>
> I am trying to write a script that sends a code to a COM port to open a till
> draw. The code at the bottom of the page (written in C) is what the suppliers
> sent as an example. I have used the SerialPort class in .Net 2.0 to try and
> send the same message. So far I have this on a button click:
>
> -------------------------------------------------------------
> Dim ComPort As New SerialPort("COM6", 9600)
> ComPort.Parity = Parity.None
> ComPort.StopBits = StopBits.One
> ComPort.DataBits = 8
> ComPort.Handshake = Handshake.None
> ComPort.Open()
> ComPort.Write("0x07")
> ComPort.Close()
> ComPort.Dispose()
> -------------------------------------------------------------
>
> The code runs without error (unless I run it on a machine that doesn't have
> COM6 installed on it) - but nothing happens.
>
> Am I passing the command in the right format?
>
> Any ideas?
>
> Thanks in advance,
> Stu
>
> -------------------------------------------------------------
> The C code example sent:
> -------------------------------------------------------------
> #include <dos.h>
> #include <stdio.h>
> #include <bios.h>
> #include <process.h>
> //
> #define CacheDrawerStatusPort  0x404a
> #define CacheDrawerCtrlPort  0x404d
> #define CacheDrawerStatusBitOffset 0x10
> #define CacheDrawerCtrlBitOffset 0x80
> //
> void ShowCacheDrawerStatus(void);
> //
> void main(void)
> {
> unsigned char CacheDrawerCtrlBit;
> int Key;
> //
> ShowCacheDrawerStatus();
> printf("Press Space key to toggle cache drawer control bit.\n");
> printf("Press Ctrl+Q key to exit.\n");
> while(1)
> {
>  while(!bioskey(1));
>  Key=bioskey(0);
>  Key&=0x00ff;
>  switch(Key)
>  {
>   case 0x20:
>    CacheDrawerCtrlBit=inportb(CacheDrawerCtrlPort);
>    CacheDrawerCtrlBit^=CacheDrawerCtrlBitOffset;
>    outportb(CacheDrawerCtrlPort,CacheDrawerCtrlBit);
>                                delay(1000);
>    ShowCacheDrawerStatus();
>   break;
>   case 0x11:
>    exit(0);
>   break;
>  }
> }
> }
>
> void ShowCacheDrawerStatus(void)
> {
> unsigned char CacheDrawerStatusBit;
> CacheDrawerStatusBit=inportb(CacheDrawerStatusPort);
> if((CacheDrawerStatusBit&CacheDrawerStatusBitOffset) ==
> CacheDrawerStatusBitOffset)
>  printf("Cache drawer is closed now.\n");
> else
>  printf("Cache drawer is opened now.\n");
> }
>
>

"Dick Grier" <dick_grierNOSPAM@.msn.com> wrote in message
news:uAO2d%23cpGHA.1600@TK2MSFTNGP04.phx.gbl...
> Hi,
>
> Two problems
>
> You cannot close the port IMMEDIATELY after (attempting) to send data.
> The close will happen before the data have been sent -- Windows buffers
> the data, then puts it in the serial UART (hardware), and this data will
> be discarded before it can be sent.
>
> The best (IMO) way to handle port open and close is to open the port when
> you start your program, and close it when the program terminates.  You do
> not have to call Dispose.
>
> However, in addition... Your write should look like this (or some
> variant):
>
>     ComPort.Write(Chr(7))
>
> Dick
>
> --
> Richard Grier, MVP
> Hard & Software
> Author of Visual Basic Programmer's Guide to Serial Communications, Fourth
> Edition,
> ISBN 1-890422-28-2 (391 pages, includes CD-ROM). July 2004, Revised March
> 2006.
> See www.hardandsoftware.net for details and contact information.
>