Re: modifying line state manually on ttyS

[Michael Buesch <freesoftwaredeveloper@web.de>]

On Monday 07 April 2003 17:51, Richard B. Johnson wrote:
> This means that you can't control TxD directly. I suggest that
> you use the parallel printer-port. This port allows you to set

That's my problem. parallel-port is used by a printer and I don't
wanna by an expensive extension card for second parport. :)

> Now, if you really need the +/- 12 volts that you think you
> will get out of a UART, please measure it first. Many new computers
> use I/O chips that only provide +/- 5 volts! Anyway, you can use the

That's no problem, because I "down-volt" it to 4.7V before using it.

> calls. You probably want to disable the SIGHUP signal before
> you muck with those bits. Some versions of Linux will send the
> hangup signal to the TTY owner even though it's not the controlling
> terminal for the process. This could cause your program to exit
> for "unknown" reasons; signal(SIGHUP, SIG_IGN) prevents such problems.

Thanks for this important information.

Regards
Michael Buesch.

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