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io ports

Posted on 2003-12-08
Medium Priority
Last Modified: 2010-04-05
i gather that the rtl stuff is depreciated. however i can't find any documentation on using streams to access the io ports. in  particular the serial and parallel ports, or maybe also usb.

please point me to the right documentation and maybe also 3rd party components that allow access to io ports.

Question by:andru
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LVL 11

Expert Comment

ID: 9902653
There is no good reason to connect streams to IO ports because usually you want to use the Win32 API functions directly.
All COM port components work that way.
USB is impossible because the USB port is nonexistent. You always talk to devices.

Accepted Solution

mgazza earned 500 total points
ID: 9906285
you cant assess the usb without a device driver the computer doesnt know how to talk to the device

but you can talk to the com or parallel port
comm is a string with ither 'COM1' ect or 'LPT1'

close the handle when your finished with it

CommFile := CreateFile(pchar(comm), GENERIC_READ or GENERIC_WRITE, 0, Nil,
                                      FILE_ATTRIBUTE_NORMAL, 0);

   if CommFile = INVALID_HANDLE_VALUE then

you can read or write to the port using readfile or writefile
look at the microsoft documentation about this
if you want to setup a braud speed ect use

if not SetupComm(CommFile, RxBufferSize, TxBufferSize) then
   showmessage('Error 1');

if not GetCommState(CommFile, DCB) then
   showmessage('Error 2');

if not BuildCommDCB(@Config[1], DCB) then
   showmessage('Error 3');

if not SetCommState(CommFile, DCB) then
   showmessage('Error 4');

with CommTimeouts do
   ReadIntervalTimeout := 0;
   ReadTotalTimeoutMultiplier := 0;
   ReadTotalTimeoutConstant := 1000;
   WriteTotalTimeoutMultiplier := 0;
   WriteTotalTimeoutConstant := 1000;

if not SetCommTimeouts(CommFile, CommTimeouts) then
showmessage('Error 5');

that will all setup your comport for reading or writting
   CommFile: THandle;
   Config : String= 'baud=19200 parity=n data=8 stop=1' +#0 ;
   CommTimeouts : TCommTimeouts;
   Data:array [0..255] of word;
   RxBufferSize = 256;
   TxBufferSize = 256;

Expert Comment

ID: 9908078
I use Async Professional for Delphi and it works great for me.
I stopped on version 3, but they went open source as far as I know...
so just have a look at source forge for more information.

Author Comment

ID: 9915133
as i guessed, but wasn't sure bout parallel port.


Expert Comment

ID: 9915412
no problem :D glad to help

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