how to set and clear RTS in a 32-bit Delphi4 (pascal) console app

[Cantor3]

Hello.

I am trying to write a very simple Delphi4 32-bit console application {$APPTYPE CONSOLE} which sets and clears the RTS pin of the COM1 RS232 serial port.

What is the simplest way to do this?

I tried writing asm code (see below) but not surprisingly I got a run-time exception (see below).

Does Delphi4 have built-in support for setting/clearing RTS? I could not find it.

Thank you.


---------begin code--------------
procedure SetRTS;
asm
mov dx, 03fch; {get COM1 MCR}
in al,dx;
or al, 2; {set RTS}
out dx, al;
end;

procedure ClearRTS;
asm
mov dx, 03fch;
in al,dx;
and al, 0fdh;
out dx, al;
end;
---------end code-------------


-------begin runtime error message-------------
Exception EPrivilege in module z.exe at 00008254.
Privileged instruction.[/QUOTE]
-------end runtime error message-------------

 

[Glenn9999]

You can't use privileged instructions within Windows NT class operating systems in writing 32-bit windows programs. To access hardware functions, you need to go through the Win32 API. See below link which describes it for serial ports.

http://www.robbayer.com/files/serial-win.pdf

For future reference, the Delphi forum is here: forum102

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