need modem control lines info

[Karl-P. Huestegge]

wht at n4hgf.Mt-Park.GA.US (Warren Tucker) writes:

>jan at bagend.uucp (Jan Isley) writes:
>>
>>I need some information on controling and determining the status of
>>modem control lines with SCO SYSV/386.  More precisely, I need to:
>>
>>1. Set DTR on.
>open the tty line
>>2. Set DTR off.
>close the line

>This is the only way to manipulate the DTR line.

>>3. Set RTS on.
>>4. Set RTS off.

>These are not directly manipulable.

>>5. Determine the state of CD.
>>6. Determine the state of CTS.
>These are not readable.

You might check RTS and CD together with the CLOCAL iocontrol. If You
unset CLOCAL and can't open the device in a suitable time, RTS or
CD are missing. If the open doesn't block, both signals are active.

You can still manipulate a blocking tty-Modemdevice with the fcntl (O_NDELAY)
feature.

-- 
Karl-Peter Huestegge                       karl at robot.in-berlin.de
Berlin Friedenau                           ..unido!fub!geminix!robot!karl