I an setting up a stratum 1 ntp server using a GPS as a reference clock. To do this, the GPS talks to the computer through one serial port for the time information and a second serial port for a pps (pulse per second) signal to condition the computer's clock. The default serial port configuration for the GPS is 4800 8N1 with no flow control. I can monitor the GPS 'sentences', from the command line with: stty --file /dev/ttyS0 4800 igncr cat /dev/ttyS0 or I cam use minicom, and monitor the data whether flow control is on or off. (BTW: the output data looks something like this: $GPGSV,3,1,11,01,00,000,,02,00,000,,03,00,000,,25,00,000,*7C $GPGSV,3,2,11,26,00,000,,27,00,000,,28,00,000,,29,00,000,*78 $GPGSV,3,3,11,30,00,000,,31,00,000,,32,00,000,,,,,*49 $PGRME,,,,,,*4D $GPRMC,142410,V,2503.715) The problem is that you occasionally need to talk to the GPS as well through the first serial port. I can do this with minicom, because I can turn off flow control, but I cannot do it from the command line and when I exit minicom, it resets the port with flow control turned on. A command sentence, say to turn off the $PGRMC sentence above that contains no useful data, would look like: $PGRMO,PGRME,0 To make matters worse, the command sentence must end with a <CR><LF> or 0D 0A hex. The questions: How do I configure the serial ports from the command line (or a shell script) or change the default setup on boot? They need to be 4800 8N1 flow control none. How do I generate a carriage return, line feed from the command line so that a command like: cat \$PGRMO,PGRME,0<CR><LF> > /dev/ttyS0 would work? Specifically, is there an escape or Alt key sequence that will generate the code for carriage return and line feed? Thank you for the help. John T
