Teledyne API Model 200A NOX Analyzer Instruction Manual, 02246, Rev. G, DCN 5247
CPU Board
The M200A Analyzer is operated by an NEC V40 microprocessor. Computer communication is
done via 2 major hardware assemblies, the V/F board and the front panel display/keyboard. The
computer's multitasking operating system allows it to control the instrument, monitor test points,
generate analog outputs and provide a user interface via the display, keyboard and RS-232 port.
These operations appear to be happening simultaneously but are actually done sequentially based
on a priority queuing system maintained by the operating system. The jobs are queued for
execution only when needed, therefore the system is very efficient with computer resources. The
M200A is a true computer based instrument. The microprocessor does most of the instrument
control functions such as valve switching and temperature control. Data collection and
processing are done entirely in the CPU with the final concentration values being sent to a D/A
converter to produce the instrument analog output.
The computer memory is divided into 3 sections: ROM memory contains the multi-tasking
operating system code plus the instructions that run the instrument. The RAM memory is used to
hold temporary variables and current concentration data. The EEPROM memory contains the
instrument set-up variables such as range and instrument ID number. The EEPROM data is non-
volatile so the instrument can lose power and the current set-up information is preserved.
4.2.4 V/F Board The V/F board is multifunctional, consisting of A/D input channels, digital I/O channels, and
analog output channels. Communication with the computer is via a STD bus interface. The
computer receives all of the instrument data and provides all control functions through the V/F
board.
4.2.5 Front Panel The front panel of the M200A is shown in Table 2-2-4. The front panel consists of a 2 line
display and keyboard, 3 status LED's and power switch. Communication with the display,
keyboard, and status LED's is done via the computer's on-board parallel port. The M200A was
designed as a computer controlled instrument, therefore all major operations can be controlled
from the front panel display and keyboard.
The display consists of 2 lines of 40 characters each. The top line is divided into 3 fields, and
displays information. The first field is the mode field. A list of operating modes is given in
Table 5-5-9.
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