Cambridge Sensotec Rapidox 1100ZR-H-PFC-E O
2
Analyser Instruction Manual
Version 1.2
11
Last printed 22/07/2015 18:08:00
The Rapidox analyser provides various analogue outputs. The standard industrial
analogue outputs (0-10V and 4-20mA) for both oxygen, and temperature (or
internal pressure) are accessible via the terminal block (6) on the rear panel.
These outputs have a 12 bit resolution (approximately 1 in 4000) and the lower
and upper values are fully user-programmable using the keypad (2) or the software
provided (section 8). In the case of oxygen, three output mode options are
provided for setting the outputs, in order to give the user maximum flexibility:
1.
LIN (ppm):
The linear oxygen output mode setting produces an output that is
scaled linearly between 0 and 10V (or 4 and 20mA). So, for example, if the
scale is set 0V = 0% O
2
and 10V = 100% O
2
then 5V would indicate an oxygen
reading of 50% O
2
. The scaling of this example is shown in the following plot,
from which other intermediate values can also be read. This setting is more
suitable for medium to high ranges of oxygen, or where the user wishes to
monitor oxygen over a narrow range.
Figure 4: Graph showing the linear output mode option for oxygen
The following general formulae can be used to calculate the oxygen from the
voltage or current outputs when set to the linear output mode:
Output type Formula for calculating oxygen from analogue output signal
0-10V
O
2
= V
out
/ 10 * (O
2H
- O
2L
) + O
2L
4-20mA
O
2
= (mA
out
– 4) / 16 * (O
2H
- O
2L
) + O
2L
Where:
O
2L
= user setting of oxygen for 0V or 4mA output
1
O
2H
= user setting of oxygen for 10V or 20mA output
1
V
out
= the measured voltage output in volts
mA
out
= the measured current output in mA
1
O
2
, O
2L
and O
2H
must all be in the same units.
"Lin(ppm)"
Linear output mode
0
1.25
2.5
3.75
5
6.25
7.5
8.75
10
0
10
20
30
40
50
60
70
80
90
100
O
2
(%)
O
2
V
o
lt
s
o
u
tp
u
t
4
6
8
10
12
14
16
18
20
O
2
m
A
o
u
tp
u
t