Re: Help on serial ports

[volker%volker-wolfram.de@localhost (Volker Wolfram)]

Emiliano GavilÃn <emilianogavilan%gmail.com@localhost> wrote:

> On Tue, Jun 22, 2010 at 12:11:15PM +0200, Volker Wolfram wrote:
> > No I try to communicate with 2 USB-RS232 Adapters and a nullmodem cable. I 
> > try
> > to send data from one /dev/ttyU0 to /dev/ttyU1 and catch the data on the 
> > last
> > device. But all fails. I tried many steps but all fails. Except one 
> > following
> > setup: one minicom client comunicates via /dev/ttyU0 and another client do 
> > it
> > on /dev/ttyU1. So I think my serial line adapters and the nullmodem cable 
> > work
> > well. But what should I do with my scripts? Can anyone help me?
> >
> > Exactly how are you communicating with the port? I wrote an SMS daemon in 
> > C. It talks to the modem via a serial port. I had to do a *lot* of low 
> > level hacking to get that port talking to me. I would be happy to post the 
> > code if it is going to help.
> > -- 
> > Michael Smith
>
> I bet the problem is that the connection cable doesn't have a Data Carrier
> Detect pin connected, and NetBSD is blocking the open() call until that signal
> is detected. This result in a never-returning [open].
>
> > here is my code for sending a character:
> > #!/usr/pkg/bin/tclsh
> >
> > set serialHandle [ open "/dev/ttyU0" r+ ]
> > fconfigure $serialHandle -translation binary -mode "9600,n,8,1"
> > fconfigure $serialHandle -encoding binary
> > fconfigure $serialHandle -blocking 0 -buffering none -handshake none
> >
> > fileevent $serialHandle writable [ puts $serialHandle "m" ]
> > close $serialHandle
>
> try this:
>
>
> #!/usr/pkg/bin/tclsh
>
> proc sendData {fd data} {
>       puts $fd $data
>       close $fd
>       exit
> }
>
> set device "/dev/ttyU0"
> exec /bin/sh -c "sleep 1 && stty -f $device clocal" &
> set serialHandle [open $device r+]
> fconfigure $serialHandle -translation binary -mode "9600,n,8,1"
> fconfigure $serialHandle -encoding binary
> fconfigure $serialHandle -blocking 0 -buffering none -handshake none
>
> fileevent $serialHandle writable [list sendData $serialHandle "m"]
> # I guess you have this line, but I'll add it anyway
> vwait forever
>
>
> > and here the code for the receiver:
> > #!/usr/pkg/bin/tclsh
> > 
> > set serialHandle [ open "/dev/ttyU1" r+ ]
> > fconfigure $serialHandle -translation binary -mode "9600,n,8,1"
> > fconfigure $serialHandle -encoding binary
> > fconfigure $serialHandle -blocking 0 -buffering none -handshake none
> > 
> > fileevent $serialHandle readable [ puts stdout [ read $serialHandle ] ]
> > close $serialHandle
>
> and this for the receiver:
>
> #!/usr/pkg/bin/tclsh
>
> proc receiveData {fd} {
>       puts [read $fd]
>       close $fd
>       exit
> }
>
> set device "/dev/ttyU1"
> exec /bin/sh -c "sleep 1 && stty -f $device clocal" &
> set serialHandle [open $device r+]
> fconfigure $serialHandle -translation binary -mode "9600,n,8,1"
> fconfigure $serialHandle -encoding binary
> fconfigure $serialHandle -blocking 0 -buffering none -handshake none
>
> fileevent $serialHandle readable [list receiveData $serialHandle]
> vwait forever
>
>
>
> Hope this helps.
> Emiliano
Hello Emiliano,

these code examples work now fine. But thanks to all helpers.

Regards,

Volker Wolfram