Teledyne 7300a - NDIR analyzer - Manual (Page 64)

4 Operation Model 7300A
4-28 Teledyne Analytical Instruments
In the autoranging mode, the microprocessor automatically responds to
concentration changes by switching ranges for optimum readout sensitivity. If the
upper limit of the operating range is reached, the instrument automatically shifts
to the next higher range. If the concentration falls to below 85% of full scale of
the next lower range, the instrument switches to the lower range. A correspond-
ing shift in the DC concentration output, and in the range ID outputs, will be
noticed.
The autoranging feature can be overridden so that analog output stays on a
fixed range regardless of the contaminant concentration detected. If the concen-
tration exceeds the upper limit of the range, the DC output will saturate at 1 V dc
(20 mA at the current output).
However, the digital readout and the RS-232 output of the concentration
are unaffected by the fixed range. They continue to read beyond the full-scale
setting until amplifier saturation is reached. Below amplifier saturation, the over
range readings are accurate UNLESS the application uses linearization over the
selected range.
To program the ranges, you must first perform the four steps indicated at
the beginning of section 4.8 Programming. You will then be in the MAIN
MENU and selecting application function screen.
Sel rng to set appl:
—> Ш1 Ш2 Ш3 CAL <—
Use the UP/DOWN key to increment/decrement the range number to 01,
02, 03, or CAL, and Enter .
Imp: CO2
FR:Ø TO:1Ø %
Use the UP/DOWN key to increment the respective parameters as de-
sired.
Use the ENTER to move from Imp: (impurity) to ppm or % to FR: (from-
lower end of ranges), and TO: (to upper-end ranges).
Last Enter will accept the values and the screen will display
OFFST/INVRT:
Standard:
ESC if your application is standard. If your application requires OFFSET
or Reversal output, ENTER will set your output as OFFSET or REVERSAL.
(See special function setup section 4.9 for more information).
. (See note below.) Repeat for each range you want to set.