Coastcom D/I Mux III System, User Manual

Page: 43 / 329

Chapter 1. System Overview and Modes of Operation
23
RS-485 Provisioning Bus Interface
Communication between the common equipment and line cards takes place over a
balanced serial bus at a data rate of 19.2 Kbps. This polled multidrop system allows only
one unit to transmit over the bus at any given time. All equipment can monitor and
receive messages simultaneously.
UART
The Universal Asynchronous Receiver/Transmitter (UART) device interfaces the
motherboard to the sub-board.
FLASH ROM
The FLASH Read Only Memory (ROM) contains the operating instructions used by the
microcontroller.
RAM
The Random Access Memory (RAM) is used by the microcontroller for “scratch pad”
memory.
Nonvolatile RAM (NVRAM)
Onboard Nonvolatile Random Access Memory (NVRAM) provides nonvolatile storage of
map information and other critical data for configuring the system. All channel card
settings and parameters are also stored in NVRAM. A 7-year lithium battery included on
the card preserves the information stored in NVRAM when power to the card is removed.
Date and Time Clock
The date and time (real time) clock provides accurate time information (day, date, hour,
minute, second) used for shelf configuration and operation. The date and time clock is
also powered by the 7-year battery.
Alarm Relay Circuits
The alarm relay circuits control and operate the relay contacts that are normally open for
the visual, audible, and minor alarms.
Alarm Cut-Off and Bypass Switch Circuits
The Alarm Cut-Off (ACO) and Bypass (BYP) circuits can be activated from front panel
switches on the MCU, or through terminal control.
LEDs
Front panel Light Emitting Diodes (LEDs) display alarm status, ACO status, and bypass
status.