USR 5687 modem

USR 5687 modem

Post by Fabricio Roch » Fri, 23 Nov 2001 12:46:35

Hi all,

        I've just bought a USRobotics 5687 internal ISA PnP modem which gave me
some headache during setup in Windows and I simply can't make the thing
work under Linux. ISA PnP modems are usually strange to set up, I know
it from my previous Wisecom modem, but it used to work after some isapnp
and setserial tricks. Now I'm having some strange behaviours with this
USR modem.

        It looks as it is correctly detected, always in IRQ 3 though Windows
accesses it through IRQ 5. isapnp configured via Linuxconf detects it
and I can assure that by the KDE Control Center. But when the kernel is
booting up, it automatically detects a /dev/ttyS2 (COM3) device too, in
IRQ 5, which, I think, is the modem serial port.

        If I try to use setserial to point /dev/ttyS2 to the board as detected
by isapnp, it shows a conflict. If I try to set up isapnp to put the
board at IRQ 5, it also will not work.

        I've browsed the web for information about that and I found out info
that this modem requires some tricks, but the pages I saw didn't help
that much. Do someone have experience which such modem??

Thank you a lot!

Fabricio Rocha
Brasilia, Brasil


USR 5687 modem

Post by Fabricio Roch » Sat, 24 Nov 2001 14:03:40

Hello all,

        I found myself a solution and right now I'm writing this from KDE News
Reader. At first I found a solution that required setup every time I turned
on the computer, but here is the automatic process if someone else have
problems like mine:

1) Add to rc.local (/etc/rc.d/rc.local in my Conectiva distro) a line like
        setserial /dev/ttyS2 port 0x2e8

        In this example, I used ttyS2 because I wanted my modem at COM3, and the
port is the one which was assigned to the modem by isapnp when the modem is

2) Edit manually /etc/isapnp.conf. It has lots of lines starting with #,
which are ignored. Find the ones without #, specially the one which assigns
an IRQ to the modem. In my case, it was set to IRQ 3, and I changed it to
IRQ 5, which was the IRQ assigned to ttyS2 by the kernel during boot stage.

        Then the thing will work forever! : ) I hope this helps someone.

Best regards,

Fabricio Rocha
Brasilia, Brasil


1. Init String for USR 5687 modem


I just bought a USR 56K 5687 OEM modem.

I do not have a manual that goes with this and the USR website is not that
helpful in getting the init string info ( expect AT&F1 ).

If you have this modem could pass on the init string that works for you.


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