Re: [PARPORT] reset // port device

From: Damien Mattei (
Date: Tue May 06 2003 - 11:18:15 EDT

  • Next message: Gregg C Levine: "Re: [PARPORT] reset // port device"

    Blaise Gassend wrote:
    > Hi,
    > 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.
    > Blaise
    > 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: )
    >>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?
    >>best regards

    Damien MATTEI
    C.N.R.S - UMR 6549 - U.N.S.A

    -- To unsubscribe, send mail to: -- -- with the single word "unsubscribe" in the body of the message. --

    This archive was generated by hypermail 2b29 : Tue May 06 2003 - 11:35:00 EDT