Re: Ada way to read/write to character file

[Michael Bode <m.g.bode@web.de>]

tmoran@acm.org writes:

>   Given timing, error conditions, dropped lines, and the likelihood of
> non-text data, I wonder how often you would actually want to do
> "sequential text I/O" on an RS232 port. 

There are all kinds of devices that are controlled by text commands
over RS232. I currently have on my table (in the lab) a pyrometer, a
temperature controller (home made), drives for optical tables, a drive
for a linear axis, 2 CCTV cameras and a scope. So I guess I will have to
do that quite often :-).

> There's also the question of
> where do you specify parity & baud rate.

Since this has to be done only once at program start one could simply
execute something like "stty -F /dev/ttyS0 ..." or "mode com1
...". Using the proper API functions is a bit more work but
better. Esp. with Windows 2k I could not get the communication to work
when I set the COM1 parameters with mode and then started my
program. Windows 98 was fine, Linux too. Timeout values have to be set
from API functions anyway. That way I discoverd the Win32 bindings
that come with gnat 3.13p are a bit old, Microsoft has changed the
definiton of the COMM_DCB struct, but the old one still works too.