Datex-Ohmeda CAPNOMAC ULTIMA, Руководство по обслуживанию

Страница: 62 / 232

CAPNOMAC ULTIMA
TM
SERVICE MANUAL 5-14
5.4
ACX measuring board
Block diagram and schematic diagram part 1
Parts layout and schematic diagram part 2
Timing diagram and schematic diagram part 3
Figure 5.7
Figure 5.8
Figure 5.9
The measuring electronics can be divided into a few functional
blocks, which are described below (See the block diagram).
CAUTION:
Do not attempt to repair or replace the pressure
transducer (Bl). Its calibration values are stored in EEPROM
(D2) and can be programmed only at the factory.
The ACX measurement board controls gas measurements. It
converts the photometer signal to digital data, calculates results and
transmits it to main CPU board. The board contains, in addition to
the 80C5lFA processor, EPROM, RAM, and EEPROM, several
analog and digital I/O functions.
Internal and external bus
The processor Dl, has access to the measurement board peripherals
(memory, A/D converter, D/A converters, etc) via an internal bus.
For communication between the CPU board and the measurement
board, there is an external bus in connector Xl. The external bus
is driven by D21 (data lines), D3 (address lines) and D18 (read and
write lines).
Memory
Memory components include 64 x 8 kbit program memory EPROM
(D4), 32 x 8 kbit low current CMOS RAM (D22) powered by a
data retention voltage generation circuit in power supply board,
and EEPROM (D2) for permanent calibration values and setup
memory.
Reference voltages
Reference voltages are established by the A/D-converter (D14)
reference voltage output (REFOUT, pin 8). This +l0 V voltage is
buffered by A2D. -10 V reference voltage is obtained by inverting
and bufl0 V with amplifier A2C.
January 15th, 1997/6