Percent Oxygen Analyzer Operation 4

4-15

Teledyne Analytical Instruments

4.6 The

Range

Function

The Range function allows the operator to program up to three concen-
tration ranges to correlate with the DC analog outputs. If no custom ranges
are defined by the user, the instrument defaults to:
Low = 0–1.00 %
Med = 0–5.00 %
High = 0–10.00 %.
The Model 3000PA is set at the factory to default to autoranging. In this
mode, the microprocessor automatically responds to concentration changes
by switching ranges for optimum readout sensitivity. If the current range
limits are exceeded, the instrument will automatically shift to the next higher
range. If the concentration falls slightly below full scale of the next lower
range, the instrument will switch to that range. A corresponding shift in the
DC percent-of-range 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 oxygen concentration detected. If the
concentration exceeds the upper limit of the range, the DC output will
saturate at 1 V dc.
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.
4.6.1 Setting the Analog Output Ranges
To set the ranges, enter the range function mode by pressing the
Range
button on the front panel.
L—1.00 M—5.00
H—10.00 Mode—AUTO
Use the < > arrow keys to blink the range to be set: low (L), medium
(M), or high (H).
Use the ∆∇ arrow keys to enter the upper value of the range (all ranges
begin at 0 %). 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 0–1 % and range 2 is set as 0–10%, range 3
cannot be set as 0–5 % since it is lower than range 2.