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APPENDIX B
Null Modem Cable Requirements
A synchronous null modem cable is a specially-configured cable that simulates
modems that are connected back-to-back. When the distance between the two host
systems is not great, you may be able to use a null modem cable instead of a
synchronous modem or a synchronous modem eliminator.
The maximum distance a null modem cable can work is determined by the
specification for your serial port interface.
There are two steps you must perform to use a null modem cable for machine
supplied clocking:
Runhsip_init (see “Configuring Internal or External Clocking” on page 30) so that
the Sun system, in the absence of a synchronous modem, supplies clocking on the
serial line.
Build or configure the cable for the null modem.
Note – Youmust run hsip_init each time you reboot your system.
The following topics are included in this appendix:
■“Configuring Internal or External Clocking” on page30
■“Building the Null Modem Cable” on page 30