[comp.sys.hp] Probs w/ 9000/800 Serial Lines

jr@einstein.dkw.com (J.R. Jesson) (04/27/91)

I have an hp9000/822 with a HP-PB 8 Line mux (HP 40299A).  I'm
having trouble setting up the mux device so that it will recognize
when my telebit trailblazer modem has lost carrier - so that it will
then hang up the interactive session.  I've wired a "CCITT" modem
cable as suggested in the documentation on the mux and I've configured
the tty0px device in both simple and ccitt mode, with the dial-out or
dial-in attribute set; in short I've tried everything I know to do.  
I would appreciate any input on this problem; the HP machine is not
supposed to be my main worry.  

J.R.

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franks@hpuamsa.neth.hp.com (Frank Slootweg CRC) (05/01/91)

See MODEM(7) for a description of CCITT and simple mode. In general you
should use a simple mode device file (even in Europe and even if you
have a modem which is CCITT compliant). In our experience in only a very
few cases (much less than 5%) CCITT mode is required. In all other cases
it creates more problems then it solves. The reason: Most "CCITT
compliant" modems are only compliant if you specifically configure them
to be so, the defaults are often not CCITT compliant.

Hope this helps.

Frank Slootweg, HP, Dutch Customer Response Center.