Polycom DOC2237A - Manual (Page 83)

MGC Hardware and Installation Manual
4-11
The Main Control Module includes several connectors. These are connected
to ports on the chassis. Two types of connectors on the rear panel provide
connections from the MGC to various external systems. These systems
include reservation systems, local or remote operator consoles, management
systems and billing systems. One connector is a standard Ethernet LAN
interface, which support operator workstations operating on LANs via TCP/
IP. The other connector is an RS-232 interface, which is used for local
diagnostics and production purposes.
An RS-232 interface connector on the front panel is provided for connecting
to operator workstations locally or remotely (via a modem). The connector is
used for local diagnostics and production purposes.
The Main Control Module Control Bus connects to the Functional Modules.
The C8M provides the interface between the Main Control Module and the
Backplane. This module also generates the MCU clock. The operating system
running on the Main Control Module uses the Processor’s internal clock
interrupts to set up its real-time clock. Sometimes, the operating system’s
clock may skip one or several interrupts resulting in a time difference
between the two clocks. In such a case, the operating system compares the
two clocks. When a discrepancy between the two clocks is detected, the
operating system updates its clock according to the Main Control processor’s
clock. This feature ensures that long-term reservations start on time.
The MGC unit can contain different types of IP network cards. The Main Control
Module operating system includes drivers for all of the cards. The Main Control
Module’s operating system automatically detects the card type. If the card is
correctly identified, the system starts up correctly. If the system fails to detect
any card type, it will start up according to the card type definition in the
system.cfg file.
This feature does not correct any time difference between the MGC Manager’s
clock (which is derived from the Windows operating system run on the operator
workstation) and the MCU internal clock.