Teledyne 300E, Инструкция по эксплуатации, Страница: 165 / 253

Model 300E Carbon Monoxide Analyzer
Instruction Manual THEORY OF OPERATION
P/N 04288 Rev: A 165
At its heart the analyzer is a microcomputer (CPU) that controls various internal
processes, interprets data, makes calculations, and reports results using specialized
firmware developed by T-API. It communicates with the user as well as receives
data from and issues commands to a variety of peripheral devices via a separate
printed circuit assembly called the Mother Board.
The Mother Board collects data, performs signal conditioning duties and routs
incoming and outgoing signals between the CPU and the analyzers other major
components.
Data is generated by a Gas-Filter-Correlation Optical Bench which outputs an
analog signal corresponding to the concentration of CO in the Sample Gas. This
analog signal is transformed into two, pre-amplified, DC voltages ( CO MEAS and
CO REF) by a Synchronous Demodulator printed circuit assembly. CO MEAS and
CO REF are converted into digital data by a unipolar, Analog-to-Digital Converter,
located on the Mother Board.
A variety of sensors report the physical and operational status of the analyzer’s
major components, again through the signal processing capabilities of the Mother
Board. These status reports are used as data for the CO concentration calculation
and as trigger events for certain control commands issued by the CPU. They are
stored in memory by the CPU and in most cases can be viewed but the user via the
front panel display.
The CPU communicates with the user and the outside world in a variety of
manners:
q
Through the analyzer’s keyboard and Vacuum Florescent Display over a
clocked, digital, serial I/O bus (using a protocol called I2C);
q
RS 232 & RS485 Serial I/O channels;
q
Various DCV and DCA analog outputs, and
q
Several sets of Digital I/O channels.
Finally, the CPU issues commands via a series of relays and switches (also over the
I
2
C bus) located on a separate printed circuit assembly to control the function of
key electromechanical devices such as heaters, motors and valves.