Hardware Flow Control is indicated whenever a printer is having buffer overruns, is losing sections of a file, or is having other problems which can't seem to be resolved. Most printers are simply more reliable under hardware flow control.

1) The Printer

• connect a terminal (set for 9600, 8-N-1, vt100 emulation) to a port on the portserver

  set conf ip=%%.%%.%%.%% subm=%%.%%.%%.%%   [%% is the correct ip number]
  set conf gateway=%%.%%.%%.%%
  

• then telnet to the portserver from your host and

  set port dev=prn ra=##			           [## is a port number]
  set flow ra=## altpin=on       [for those ports using 8 wire RJ45 cable]
  set flow ra=## cts=on ixon=off ixoff=off    
  

  4) Options on the Unix Server

  LPD

  The PortServer II has an 'lpd' protocal running. By setting up a remote print spooler from unix, you can then print directly to the 'lpd' protocol on the PS II. This is only on the PS II, not the PortServer. Refer to the PortServer II Users Guide for help in setting this up.

  Remote Commands

  Another simple way to print is by piping thru a remote command. Typical remote commands such as telnet, rcmd, rsh (unrestricted), remsh. Several examples are below: The telnet example uses "2016" as the port address, 20xx is the TCP/IP service numbers the portserver uses, and 16 is the actual port on the portserver.

  cat /etc/passwd | telnet portserver_name 2016
  cat /etc/passwd | rsh portserver_name 16
  cat /etc/passwd | rcmd portserver_name 16

  This can also be used thru the print spooler. The below example shows a common way to use this thru a SCO Unix print spooler. Other Unixes may need to be setup differently, this is just one example:
  • Create a direct-connect serial printer. Destination device is /dev/null.
  • Edit the interface script. For SCO, it's /usr/spool/lp/admins/lp /interfaces/printer_name. This may be different for other unix's.
  • Encapsulate the script and pipe it. Add in a

    (

    at the beginning of the script. Then add the following line at the end of the script, but before 'exit 0'

    ) | rcmd portserver_name 16

  RTTY

  There is also an 'rtty' program provided from Digi. This was written years ago and is provided "AS IS" (Meaning no further development, enhancements, bug fixes will be done). 'rtty' will attach a specific pseudo device to a port on the portserver. CAUTION: The 'rtty' program will only work with BSD style pseudo devices, not streams. Examples of the 'rtty' program are in the PortServer/PortServer II Users Guide. 'rtty' source and a few compiled versions are on the Digi ftp server.

  Named Pipes

  NOTE:Not all versions of Unix allow named pipes to be used for this application.

  First we create the named pipe:

          mknod /dev/a_named_pipe p

  Then we edit /etc/inittab:

          d1:23:respawn:sleep 99999999 >/dev/a_named_pipe
          d2:respawn:rcmd portserver_name 4 
  These lines use the named pipe and keep it open continuously.  You
  can also replace "rcmd" with other remote cmds (depending on the OS
  different remote cmds work better) such as:  rsh(unrestricted), remsh,
  or telnet(last resort).  The above example shows portserver_name.  You can
  use the portserver name or ip address.  The port number either be the
  physical port number, or if you are using telnet, 2000+the_port_number, 
  as in the Remote Commands Option above.