Teledyne API Model 200AH NOX Analyzer Instruction Manual, 06492, Rev. G2
9-41
C. The M200AH will display a voltage near 1% of the voltage range set in the above
procedure. Adjust R27 until the displayed voltage matches the DVM voltage, then press
ENTR.
D. The M200AH will display a voltage near 90% of the voltage range set in the above
procedure. Adjust R31 until the displayed voltage matches the DVM voltage, then press
ENTR. This step calibrates the instrument A/D converter to the external DVM.
The next task is to calibrate each of the 4 DAC output channels. The NEXT - PREV buttons
allows selection of any of the 4 D/A channels. DAC0 - the NOX channel - is displayed first.
E. The SET button has 2 functions, first to select the output mode - voltage or current. Press
VOLT and CURR depending on the type of output desired. - Remember, the VOLT or
CURR setting must match the switch and jumper settings made previously. Second,
the voltage output can be biased up to 10% of the selected range with the OFFSET
parameter. Just key in the desired offset, or press EXIT to leave the OFFSET at zero.
F. For DAC channels in VOLTAGE mode, press CAL. This will cause the instrument to
automatically calibrate the channel.
G. For DAC channels in current mode, first connect a 250 ohm resistor in series with a
current meter to the correct pair of terminals on the rear panel, see Table 9-6 for terminal
assignments. Press CAL. The instrument will output 4 mA to the rear panel terminals. UP,
DOWN and ENTR buttons will be displayed. Press the UP - DOWN buttons until the
correct reading is displayed on the meter, then press ENTR. 20 mA is then output to the
rear panel. As before, press the UP, DOWN buttons to get the correct reading, then press
ENTR.
H. To go the next channel press the NEXT button and follow the previous steps starting with
step - f. Proceed through all 4 DAC channels, then exit. To back up to previously
calibrated channels, press the PREV button.
9.3.3.2. Changing Output Voltage Ranges
Several different output voltage ranges can be selected by switch settings on the V/F board. See
Figure 9-4. If you change the analog output voltage range, the power to the instrument should be
turned off, then on and a DAC calibration performed (Section 9.3.3.1).