Emerson ControlWave Instruction Manual page 12

ControlWave Instruction Manual (CI-ControlWave)
CPU Backup Battery The CPU module includes a 3.6V, 950 mA-hr lithium
CPU Memory There are several different types of memory used on the CPU module:
1-6
This battery provides backup power for the real-time clock, CMOS
RAM (within the microprocessor) and the system's Static RAM
(SRAM).
Boot/Downloader FLASH
Boot/download code is contained in a single 512 Kbyte FLASH chip.
Boot FLASH also holds the value of soft switches, audit/archive file
configurations, and user account and port information.
FLASH Memory
The CPU module contains 32 MB of FLASH memory. The FLASH
memory holds the system firmware and the boot project. Optionally
FLASH memory also stores the zipped ControlWave project (*.zwt),
user files, and historical data (audit/archive files).The FLASH does not
support hardware write protection.
System Memory (SRAM)
The CPU module has 2 MB of static random access memory (SRAM).
During power loss periods, SRAM enters data retention mode (powered
by the CPU backup battery). Critical system information that must be
retained during power outages or when the system has been disabled for
maintenance is stored here. This includes the last states of all I/O points,
audit/archive historical data (if not stored in FLASH), the values of any
variables marked RETAIN, the values of any variables assigned to the
static memory area, and any pending alarm messages not yet reported.
SDRAM
The CPU module contains 64MB of synchronous dynamic random
access memory (SDRAM). SDRAM holds the running application
(ControlWave project) as well as a copy of system firmware and the
current values of any variables not marked RETAIN or stored in the
static memory area. This allows the system to run faster than it will
from the SRAM memory. SDRAM is not battery-backed.
CMOS RAM
The Elan microprocessor includes 124 bytes of complementary metal
oxide semiconductor (CMOS) RAM to hold various internal
parameters.
Introduction
½ AA
battery.
Revised Nov-2010