Teledyne API Model 200AH NO
X
Analyzer Instruction Manual, 06492, Rev. G2
4-7
4.2.5. V/F Board
The computer CPU board communicates via 2 major hardware assemblies. These are the V/F
board and the front panel display/keyboard. The V/F board communicates with the CPU via the
STD-100 bus.
The V/F board includes of A/D input channels, digital I/O channels, and analog output channels.
The computer receives all of the instrument data and provides all control functions through the
V/F board.
4.2.6. Front Panel
The front panel of the M200AH is shown in Figure 2-5. 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 computers on-board parallel port. The M200AH 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.
The center field displays TEST values. The TEST functions allows you to quickly access many
important internal operating parameters of the M200AH. This provides a quick check on the
internal health of the instrument. The right hand field shows current concentrations values of
NO, NO
X
, and NO
2
.
The M200AH can operate in any of 3 different sampling modes - NO only, NO
X
only, and
NO/NO
X
switching mode. For the NO or NO
X
only modes just the single gas being measured is
displayed. For the NO/NO
X
switching mode, the display scrolls between the NO, NO
X
, and NO
2
concentration values every 4 seconds.
4.2.6.1. Keyboard
The second line of the display contains eight fields, each field defines the key immediately
below it. By redefining the keys dynamically it is possible to simplify the instrument electronics
and user interface.
4.2.6.2. Status LED's
At the right of the display there are 3 status LED's. They can be in three states, OFF, ON, and
Blinking. The meanings of the LED's are given in Table 4-2.
