4-20Ma Analogue Output; Modbus - CompAir CN2-20P Mode D'emploi

3.6.6 4–20mA Analogue Output
Terminals Description
Positive
Analyser - #6
Negative
Analyser - #7
The oxygen content detected by the generators internal analyser may be re-transmitted to external peripherals using the 4-20mA linear analogue
output. The output is a linear current source, with 10 bit resolution, which increases from 4mA (Zero Oxygen) to 20mA (Full Scale Deflection). The
FSD of the internal analyser is factory set to a default value of twice the generators specified purity. For % purity generators the maximum FSD is
set to 6%. The oxygen purity setting of the generator is marked on the rating plate. The table below shows the correlation between the purity
settings of the generator and the output current.
It is recommended that the cable used for the 4-20mA Analogue Output is screened twisted pair. Ferrites should be added to the cable, using 1
turn, either side of the shroud cable gland. It is recommended that the cable used does not exceed 30m in length. Suitable ferrites are available
from Wurth Electronics (P/N. 74271633S).
Full Scale Deflection
Generator
Purity
4mA
5ppm 0
10ppm 0
50ppm 0
100ppm 0
250ppm 0
500ppm 0
0.1% 0
0.4% 0
0.5% 0
1% 0
2% 0
3% 0
4% 0
5% 0

3.6.7 MODBUS

Terminals Description
RS485 MODBUS - A
For MODBUS communication setup details refer to dh
publication 176500120
RS485 MODBUS - A
The generator's controller is capable of supporting direct Modbus communication via its integral RS485 connection. This industry standard
connection allows multiple generators to communicate with a remote Modbus master on a network up to 30m in length. The generator can be
programmed with its own unique address, to allow multiple generators to be connected to an existing network.
Resolution
- 20mA
- 10ppm 1ppm
- 20ppm 1ppm
- 100ppm 1ppm
- 200ppm 1ppm
- 500ppm 1ppm
- 1000ppm 1ppm
- 0.2% 0.01%
- 0.8% 0.01%
- 1% 0.01%
- 2% 0.01%
- 4% 0.01%
- 6% 0.01%
- 6% 0.01%
- 6% 0.01%
Cable size
3 - 7mm
= 1.6mA
= 0.8mA
= 0.16mA
= 0.08mA
= 0.032mA
= 0.016mA
= 0.8mA
= 0.2mA
= 0.16mA
= 0.08mA
= 0.04mA
= 0.026mA
= 0.026mA
= 0.026mA
Cable size
3 - 7mm
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