Placing Units On Top of Each Other 25Stacking Units 26Stacking Two Units 26Stacking Up To Four Units 27The Power-up Sequence 29Connecting a Redundant Power System 29Powering-up the Switch 3300 FX 29Checking for Correct Operation 29Choosing the Correct Cables 30Solving Problems Indicated by LEDs 31Managing the Switch 32A S AFETY I NFORMATIONImportant Safety Information 34L’information de Sécurité Importante 36Wichtige Sicherheitsinformationen 38B P IN- OUTSNull Modem Cable 41PC-AT Serial Cable 41Modem Cable 42RJ45 Pin Assignments 42C TECHNICAL SPECIFICATIONSD TECHNICAL SUPPORTOnline Technical Services 47World Wide Web Site 473Com Knowledgebase Web Services 473Com FTP Site 483Com Bulletin Board Service 483Com Facts Automated Fax Service 49Support from Your Network Supplier 49Support from 3Com 49Returning Products for Repair 51