HP OpenVMS Systems

Raw terminal I/O via LAT?

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The Question is:

 
I have a detached proccess that needs to read raw data from a LAT port
if I set the terminal to /PASTHRU I lose characters.
 
If I use /PASSALL I don't lose any.
 
IF /PASSALL is an obsolete setting for a terminal what are the equivalent
 
/PASTHRU does not function the same as /PASSALL. ?
 
 
 

The Answer is :

 
  /PASSALL is obsolete. /PASTHRU is very similar, save the flow control
  characters ^S and ^Q are processed by the terminal driver. With /PASTHRU,
  the interpretation of ^S and ^Q is determined by TTSYNC and HOSTSYNC.
 
  So, /PASTHRU/NOTTSYNC/NOHOSTSYNC means all characters are passed as
  binary characters in both directions. /PASTHRU/HOSTSYNC/TTSYNC will
  receive all characters except flow control which will work in both
  directions. Note that the default behaviour and the default setting
  for processing flow control is /TTSYNC/NOHOSTSYNC.
 
  Data loss (obviously) indicates a mismatch between the input data stream
  and the ability of the program to read input. If the sender understands
  flow control, /HOSTSYNC may help. If not, you may want to consider
  increasing the size of the typeahead buffer (SYSGEN parameter
  TTY_TYPAHDSZ or enabling ALTYPAHEAD and TTY_ALTYPAHD), and/or
  multibuffering using asynchronous $QIOs, and/or the implementation of
  software flow control (or hardware flow control, if the controllers
  permit it).
 

  

     

     
answer written or last revised on ( 16-NOV-2000 )
     
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