0049-1200-XXX RM16M – USER’S GUIDE 12/29/2010
Rev. C
Page 14
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CHAPTER THREE – OPERATION
The Data Shelf accepts leased line, PSTN, and DDS-type modems. Leased line modems operate on
conditioned or unconditioned leased lines. PSTN-type modems operate on the dial-up network and have
features that allow establishment of dial-up circuits and data transfer. Some modems can operate on
either leased lines or PSTN.
Modems designed for use in the Data Shelf have a standardized interface (EIA-232C or D) that provides
for orderly calling, answering, and data modes. Many of the modems also have automatic dialing and
answering capabilities.
TEST MODES
Each plug-in modem card has a switch or switches that provide for modem testing. Test features are
described in the manual for the modem.
FRONT PANEL INDICATORS
Each PC card has Light Emitting Diode (LED) indicators that can be viewed through the transparent
front panel. With the front panel lowered, the modem controls can be accessed.
Most modems have LEDs mounted on the front edge of the card to indicate the status of various EIA-
232 interface functions. The LEDs are described in the manual for the modem.
Some PC cards have a Liquid Crystal Display (LCD) for observing modem status or selecting options
using pushbuttons on the modem front panel. The LCD functions are explained in the manual for the
modem.