4 Operation Model 3000TA-XL-EU
4-20 Teledyne Analytical Instruments
concentration 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 concentra-
tion are unaffected by the fixed range. They continue to read accurately with
full precision. See Front Panel description in Chapter 1.
The automatic air calibration range is always 0-25 % and is not pro-
grammable.
4.7.1 Setting the Analog Output Ranges
To set the ranges, enter the range function mode by pressing the
Range button on the front panel.
L—1 M—10
H—100 Mode—AUTO
Use the < > arrow keys to blink the range to be set: low (L), medium
(M), or high (H).
Use the Δ∇ arrow keys to enter the upper value of the range (all ranges
begin at 0 ppm). Repeat for each range you want to set. Press Enter to
accept the values and return to Analyze mode. (See note below.)
Note: The ranges must be increasing from low to high, for example, if range
1 is set as 0–100 ppm and range 2 is set as 0–1,000 ppm, range 3
cannot be set as 0– 500 ppm since it is lower than range 2.
Ranges, alarms, and spans are always set in ppm units (over the entire
0-250,000 ppm range), even though all concentration-data outputs change
from ppm units to percent when the concentration is above 10,000 ppm.
4.7.2 Fixed Range Analysis
The autoranging mode of the instrument can be overridden, forcing the
analyzer DC outputs to stay in a single predetermined range.
To switch from autoranging to fixed range analysis, enter the range
function by pressing the Range button on the front panel.
Use the < > arrow keys to move the blinking over AUTO.
Use the Δ∇ arrow keys to switch from AUTO to FX/LO, FX/MED, or
FX/HI to set the instrument on the desired fixed range (low, medium, or
high).