Teledyne API Model 200A NOX Analyzer Instruction Manual, 02246, Rev. G, DCN 5247
9.1.3.5 Analog Out Step Test
The Step Test is used to test the functioning of the 4 DAC outputs on the V/F board. The test
consists of stepping each analog output 0-20-40-60-80-100% of the output. If the analog outputs
are set for 0-5V full scale the outputs would step 0-1-2-3-4-5 VDC. The stepping can be halted at
any value by pressing the key under the percentage on the front panel. When the test is halted,
square brackets are placed around the percentage value in the display. Pressing the key again
resumes the test. This test is useful for testing the accuracy/linearity of the analog outputs.
9.1.3.6 DAC Calibration
The Digital to Analog Converters (DAC) are calibrated when the instrument is set up at the
factory. Re-calibration is usually not necessary, but is provided here in case the V/F board needs
to be replaced and re-calibrated. The procedure for using the DAC Calibration routines are in the
Troubleshooting Section 9.3.3.1.
9.1.3.7 RS-232 Port Test
This test is used to verify the operation of the RS-232 port. It outputs a 1 second burst of the the
ASCII letter 'w'. During the test it should be possible to detect the presence of the signal with a
DVM on pin 2 or 3 (depending on the DTE/DCE switch setting) or by the flickering of the red
test LED. A detailed procedure is given in the Troubleshooting Section 9.3.2.
9.1.4 M200A Internal Variables The M200A software contains many adjustable parameters. Most of the parameters are set at
time of manufacture and do not need to be adjusted for the lifetime of the instrument. Some of
the variables are user adjustable, they are listed in Table 9-9-5.
To access the VARS menu press SETUP-MORE-VARS-ENTR. Use the PREV-NEXT buttons
to select the variable of interest, then press EDIT to examine/change the value, then press ENTR
to save the new value and return to the next higher menu. If no change is required, press EXIT.
TPC_ENABLE
The M200A has temperature and pressure compensation. T/P comp adjusts the output of the
instrument for changes in sample temperature, reaction cell pressure, and atmospheric pressure.
The sample temperature is controlled by the temperature of the reaction cell. The setpoint is 50
C, and the value of the adjustment parameter is equal to 1.0000 when the reaction cell
temperature is 50 C. The temperature compensation increases sample concentration with
increasing temperature to compensate for the drop in density of gas in the reaction cell.
9-18
PRINTED DOCUMENTS ARE UNCONTROLLED