Emerson Process Management ControlWave XFC - Manual (Page 20)

1-6 / Introduction CI-ControlWave XFC
1.3.2 ControlWave XFC Function Module
Internally the circuit boards are stood-off and mated to a Terminal Plate via an assembly
called the Function Module. The Function Module is secured to the inside of the
ControlWave XFC case via four scews. To replace a printed circuit board, the rear cover
must first be removed before removing the four screws that secure the Function Module.
Once the Function Module has been removed, the individual circuit boards are accessable
for removeal/replacement.
1.3.3 CPU Board Assembly
The multilayer CPU Board provides ControlWave XFC CPU, I/O monitor/control, memory
and communication functions. ControlWave XFC CPU Boards operate over an extended
temperature range with long-term product reliability.
ControlWave XFC CPU Boards are based on a 32-bit ARM9TDMI RISC Core Processor.
The CPU Board is specified to operate with a system clock speed of 14 MHz. The
Microcontroller is packaged in a 256-pin Plastic Ball Grid Array. In addition to the
microprocessor, memory and control logic, the CPU Board includes one fixed RS-232
communication Port (COM1), one 2-wire RS-232 communication port (Local Port) and a
two-wire RS-485 communication port (COM3). CPU Memory consists of 2MB of battery
backed Static RAM (SRAM), 512kB Boot/Downloader FLASH and 8MB simultaneous
read/write FLASH. Interface to field I/O is provided through an I/O Bus Connector.
CPU Boards are provided backup power via a coin cell socket that accepts a 3.0V, 300mA-hr
lithium battery. This 3.0V battery provides backup power for the real-time clock and the
system’s Static RAM (SRAM). Backup power is enabled when the Battery Backup Jumper
JP1 is installed.
If the 3.3Vdc that powers the unit goes out of specification (VCC-10%), a supervisory circuit
on the CPU is used to switch to battery power. For maximum shelf life, the battery may be
isolated from the circuit by removing the Backup Battery Jumper JP1 from position 1 to 2
and then storing it on either pin. If the Real-time clock looses its battery backup a
ControlWave Designer system variable bit (_QUEST_DATE) is set. This bit can be used to
post a message or alarm to the PC (see the ‘Systems Variables’ section of the ControlWave
Designer Programmer’s Handbook D5125).
The system SRAM is specified to have a standby current of 40:A maximum (plus 2uA for
the RTC). For a system containing 2MB of System SRAM, a worst-case current draw of
42:A allows a battery life of approximately 7142 hours.
LCD Interface hardware consists of a MSP430F436 micro controller and a contrast circuit
utilizing a small potentiometer (R43). The micro controller is responsible for the LCD
initialization sequence and control via commands from the SPI port.
+1.8Vdc, used by the ARM microprocessor, is generated on the CPU Module (derived from
the regulated 3.3Vdc logic power).