6-2Additional Modem Information
External Serial Modems
IRC supports most external high-speed serial modems. Some modems, like the Compaq Microcom 510, offer both a serial and parallel (APT) interface. Such modems must be connected through the serial interface to operate correctly with IRC.
External modems are cabled to the managed server using a standard straight- through DTE to DCE style cable. A standard DB-9F to DB-25M cable can be used and there are no specific requirements specific to IRC.
Important Tip
Most external modems offer modem state indicator lights, which can be useful troubleshooting tools, particularly if you are configuring IRC for the first time. If IRC is configured for the proper COM port, the TR or DTR indicator should be illuminated shortly after the Compaq ProLiant splash screen is displayed during power-on-self-test (POST). The AA indicator indicates that the modem has been placed in auto-answer mode. If the modem has not been pre- configured (through switches on the modem) for auto-answer mode, this signal should also be illuminated shortly after the TR indicator. This indicates that IRC can communicate with the modem and the modem has correctly received the auto-answer string configured through the Compaq System Configuration Utility. If the managed server is running Windows NT as its primary operating system, this indicator can also reflect the ownership of the modem in the shared configuration. Windows NT 4.0 generally does not program the modem for auto-answer mode. As a result, if the AA indicator is illuminated after Windows NT has booted, IRC currently owns the modem. Similarly, if the AA indicator is not illuminated, the modem is currently in use by the operating system.