Cpu; Optical Bench & Gfc Wheel - Teledyne 300E Instruction Manual

THEORY OF OPERATION

10.3.2. CPU

The Model 300E's CPU is a, low power (5 VDC, 0.8A max), high performance, 386-
based microcomputer running MS-DOS. Its operation and assembly conform to the
PC/104 Specification version 2.3 for embedded PC and PC/AT applications. It has 2
MB of DRAM on board and operates at 40MHz over an internal 32-bit data and
address bus. Chip to chip data handling is performed by two 4-channel DMA
devices over data busses of either 8-bit or 16-bit configuration. The CPU supports
both RS-232 and RS-485 Serial I/O.
The CPU includes two types of non-volatile data storage.
Disk On Chip
While technically an EEPROM, the Disk –on-Chip (DOC), this device appears to the
CPU as, behaves as, and performs the same function in the system as an 8MB disk
drive. It is used to store the operating system for the computer, the T-API
Firmware, and most of the operational data generated by the analyzer's Internal
Data Acquisition System (iDAS - see Section 6.10).
Flash Chip
Another, smaller EEPROM used to store critical calibration and configuration data.
Segregating this data on a separate, less heavily accessed chip significantly
decreases the chance of this key data being corrupted.
10.3.3. Optical Bench & GFC Wheel
Electronically. the Model 300E's optical bench, GFC wheel and associated
components do more than simply measure the amount of CO is present in the
Sample Chamber. A variety of other critical functions are performed here as well.
Sample Gas and GFC Temperature Control
Because the temperature of a gas affects its density and therefore the amount of
light absorbed be that gas it is important to reduce the effect of fluctuations in
ambient temperature on the Model 300E's measurement of CO. To accomplish this
both the temperature of the Sample Chamber and the GFC Wheel are maintained at
constant temperatures above their normal operating ranges.
Bench Temperature : To minimize the effects of ambient temperature variations on
the sample measurement, the Sample Chamber is heated to 48°C (8 degrees above
the maximum suggested ambient operating temperature for the analyzer). A strip
heater attached to the underside of the chamber housing is the heat source. The
temperature of the Sample Chamber is sensed by a thermistor, also attached to the
Sample Chamber housing.
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Model 300E Carbon Monoxide Analyzer
Instruction Manual
P/N 04288 Rev: A