3600 Analyzer for O
2
Measurement—Operator’s Manual 23
3600O2.OM.E9903
Or, shown graphically (for 4–20 mA):
The output saturates at 5 V or 20 mA whenever the measured concentration is
equal to or exceeds the upper limit AH. Similarly, it remains blocked at 0 V, 0 mA,
or 4 mA if the concentration is equal to or less than the lower limit AL.
The analog output also shows these extreme values under other conditions:
Analog output Explanation
0 Volts, 0 mA or 4 mA Menu, negative value, analog output low limit, thermal cutoff,
or underrange
0 Volts < Signal < 5 Volts,
0 (or 4) mA < Signal < 20 mA
Normal operating condition
5 Volts or 20 mA Overrange, analog output high limit, or sensor disconnected
Temperature output
An analog signal representative of the sample temperature is also available at the
analog output. This varies linearly with the measured temperature in the range -20
to 100 °C, according to the following formulae:
0–20 mA T (°C) = -20 + 6 * I
T (°F) = -4 + 10.8 * I
T (°K) = 253.15 + 6 * I
4–20 mA T (°C) = -20 + 7.5 * (I - 4)
T (°F) = -4 + 13.5 * (I - 4)
T (°K) = 253.15 + 7.5 * (I - 4)
0–5 V T (°C) = -20 + 24 * V
T (°F) = -4 + 43.2 * V
T (°K) = 253.15 + 24 * V
Pressure output
An analog output signal is also available for sample pressure measurements. This
is a linear output, from 0 to 5000 mbar. This output is valid only during
measurements made in “fractional” units, that is, when the “pmv:%V” units have
been selected from the “Modify Options/ Display Units” menu.
0–20 mA Pressure, mbar = 250 * I
4–20 mA Pressure, mbar = 312.5 * (I–4)
0–5 Volts Pressure, mbar = 1000 * V
Range output
The range output furnishes an additional analog signal of 0–20 mA, 4–20 mA, or
0–5 V, enabling further interpretation of the signal on the gas concentration analog
output. This additional signal is explained in the following table:
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