charles@sifvx6.sinet.slb.com (10/25/89)
I have a problem on a SUN3/60 OS3.5 serial link from /dev/ttya to a plotter which uses XON/XOFF for flow control. If someone cycles the plotter power in mid-plot (eg to unblock the paper feed), the serial line hangs because the SUN is waiting for XON (^Q) and the plotter is not clever enough to send XON when power is restored. I use the following script to send files... (stty -even;stty -odd;stty -echo;cat $1) > /dev/ttya where $1 is the file name. If I kill the process, it does not unblock the serial line. If I do a kill -1 1 it does not clear the buffer. Nothing works except reboot or disconnect /dev/ttya and reconnect to a terminal and type SPACE,RETURN or ^Q, which empties the buffer onto the screen. Any ideas on clearing the buffer from the SUN end or improving the script would be much appreciated.
bill@ibmpcug.co.uk (bill birch) (11/15/89)
In article <21267@adm.BRL.MIL> charles@sifvx6.sinet.slb.com writes: > I have a problem on a SUN3/60 OS3.5 serial link from /dev/ttya to a plotter > which uses XON/XOFF for flow control. If someone cycles the plotter power in > mid-plot (eg to unblock the paper feed), the serial line hangs because the SUN > is waiting for XON (^Q) and the plotter is not clever enough to send XON when I have had similar problems in the past, but with the Baud rate. The trick is to sleep a process on the device thusly: sleep 1000000 >/dev/tyya & What happens is that when the last process that was using the device Hope this helps.