Blaise Gassend wrote:
> When you say that the lines are "open" or "closed", what exactly do you
> mean. If by open you mean not connected, and by closed you mean
> connected to ground, then that could be the source of your problem. You
> should be connecting the lines to 0V or to +5V to generate signals (you
> could get the +5V from one of the output lines of the port if you want).
yes it's like that it has been connectd by someone else,not me, and the
system worked well with a PC/XT under DOS and 2 // card during 3 years ,
i connected the system to a 486 PC under linux and rewrite the program
for linux and it worked well during 1 year with the built in // port,
then few months ago i add another // board (already used on the PC /XT)
and it still worked for some months, but now the data read on both //
card are erratic , if i reboot the linux system the data are corrects
for some hours, but became invariant after.
I don't think there is a problem with the external electronic connection
as it uses the +5 V from output lines and worked well in the past and
still works well after software reboot .
> When you leave the line disconnected (open) you could get a variety of
> strange behaviors depending on your exact hardware implementation.
> Quoted from Damien Mattei on Tue, May 06, 2003 at 09:45:48AM +0200.
>>i wrote a litte soft for monitoring alarms connected to // port under
>>linux.( see: http://www-iag.unice.fr/guardian/guardian.html )
>>it's a system quite simple if the circuit on one of the 5 lines (BUSY,
>>PAPER OUT, SELECT, AUTOFEED, ERROR) is open the data read is true and
>>false if it is closed.It worked well during one year, but now the data
>>are always read as false, so if an alarm occured it will not be
>>monitored as before. The problem is that it happens randomly ,on any
>>lines, and randomly after a period of time,when it happens it is not
>>reversible until i reboot the system with no power off needed.
>>So the linux kernel (or the BIOS?) seems to be able to do a soft reset
>>on the // port at boot time, if i can do this reset in my own program
>>the system will work again but i can't find on the internet how to do
>>this , perheaps someone in the mailing list know that or have an advice?
-- Damien MATTEI C.N.R.S - UMR 6549 - U.N.S.A mailto:firstname.lastname@example.org http://www-iag.unice.fr/
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