Sun Microsystems Interface Adapter manual Null Modem Cable Requirements

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A P P E N D I X 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:

Run hsip_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 – You must run hsip_init each time you reboot your system.

The following topics are included in this appendix:

“Configuring Internal or External Clocking” on page 30

“Building the Null Modem Cable” on page 30

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Contents Sun Microsystems, Inc Please Recycle Contents Cable Pin Assignments & Signals SunVTS Diagnostic Testing Page Figures Page Tables Page FCC Class a Notice Regulatory Compliance StatementsICES-003 Class B Notice Avis NMB-003, Classe B CCC Class a Notice Page Declaration of Conformity Page How This Book Is Organized PrefaceShell Prompts Using Unix CommandsRelated Documentation Typographic ConventionsThird-Party Web Sites Documentation, Support, and TrainingSun Welcomes Your Comments Product Description Product OverviewSunHSI/U Adapter Features1Hardware and Software Requirements Hardware and Software RequirementsPage Installation Process SunHSI/U Adapter InstallationTo Install the Adapter External Cabling RS-232 to RS-449 Connections Page Installation Overview SunHSI PCI Software Installation1SunHSI PCI Software Directories and Files Verifying the Software and Hardware Requirements Before Installing the SoftwareTo Remove Older Versions of the Software To Install the SunHSI Software Installing the SoftwareAt the ok prompt, type the boot command with the -roption To Test the Installation Configuring the SoftwareTo Configure for Point-to-Point Protocol Edit the /etc/netmasks file as follows Hsipinit Utility SunHSI UtilitiesOperating Modes Options T1 Compatibility OptionsHdlc Mode Hsiploop Utility Hsipstat Utility Page Pin Assignments Cable Pin Assignments & SignalsDCD1A Appendix a Cable Pin Assignments & Signals RTS4A RS-449 Interface Signals Interface SignalsPage Null Modem Cable Requirements Building the Null Modem Cable Configuring Internal or External ClockingRS-449 Null Modem Cable RS-449 SignalsPage Appendix B Null Modem Cable Requirements Figure B-3X.21 to RS-449 Converter To RS-449 ConverterData Signal Inversion T1 Inverted Data and Clock SignalsHdlc Zero Insertion Algorithm Bipolar with 8-Zero SubstitutionClock Signal Inversion Page Using the SunVTS sunlink Test SunVTS Diagnostic TestingPage Man Pages Viewing the Man PagesTo View Man Pages in the C Shell Environment Make the changes effective in your current window To View Man Pages in Bourne or Korn Shell EnvironmentsGlossary Page Index