EC150 CO
2
/H
2
O Open-Path Gas Analyzer
5
4.6.2 EC100 Outputs
The EC100 outputs data in one of four types: SDM, USB, RS-485, or analog.
In general, Campbell Scientific recommends that SDM be used if a Campbell
Scientific datalogger is collecting data. However, RS-485 output is
recommended over SDM if cable lengths exceed 100 meters. If a PC is being
used as the data collection platform, USB and RS-485 are suitable outputs.
Information for SDM, the preferred output, is detailed below. See Appendix
(p. C-1)
, for USB, RS-485, and analog outputs.
4.6.2.1 SDM Output
To use SDM data output, connect an SDM communications cable from the
(p. 22)
) to an SDM port on a
CR6, CR1000X, CR1000, CR3000, or CR5000 datalogger. On CR1000
dataloggers, the SDM port is made of terminals C1 – C3. The default SDM
port for CR6 and CR1000X dataloggers is made of terminals C1 – C3, though
it can be changed with the
SDMBeginPort()
instruction. On CR3000 and
CR5000 dataloggers, the SDM protocol uses SDM-dedicated ports SDM-C1,
SDM-C2, and SDM-C3.
Each SDM device on the SDM bus must have a unique address. The EC150
has a factory default SDM address of 1, but may be changed to any integer
value between 0 and 14 (see Appendix
SDM Address
(p. A-2)
The sample rate for SDM output is determined by the datalogger program.
Data are output from the EC100 when a request is received from the datalogger
(for example, a
prompted
output mode). The number of data values sent from
the EC100 to the datalogger is also set by the user in the datalogger program.
CRBasic
, the programming language used by Campbell Scientific dataloggers,
uses the
EC100()
instruction to get data from an EC150. This instruction is
explained in greater detail under Appendix
(p. A-1)
, and in
EC100 Configure() Instruction
(p. A-9)
.
4.7 Automatic Heater Control
An advantage of the EC150’s low power consumption (5W) is that the
instrument remains at a temperature very close to ambient air temperature,
which is an important feature for eddy-covariance measurements. Under some
environmental conditions, however, the analyzer can become colder than
ambient air temperature which may increase the likelihood of frost or
condensation building on the optical windows. This will affect signal strength.
The EC150 design includes internal heaters located at the optical windows,
which aid in minimizing data loss during these specific environmental
conditions.
An automatic heater control algorithm can be activated from either
Device
Configuration Utility
or
ECMon
by putting in a value of
−
2, or deactivated by
putting in a value of
−
1.
The algorithm uses the internal heaters to maintain a
temperature that is a couple of degrees above the ambient dewpoint (or frost
point) to prevent condensation and icing from forming on the surface of the
optical windows.
1
Automatic heater control is available in EC100 OS version 4.07 or greater and is turned on by
default starting with the OPEC program version 3.2.
Summary of Contents for EC150
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Page 67: ...Appendix B Filter Bandwidth and Time Delay B 4 ...
Page 75: ...Appendix D Useful Equations D 4 ...
Page 76: ...E 1 Appendix E Safety Data Sheets SDS E 1 Molecular Sieve Type 13X ...
Page 77: ...Appendix E Safety Data Sheets SDS E 2 ...
Page 78: ...Appendix E Safety Data Sheets SDS E 3 ...
Page 79: ...Appendix E Safety Data Sheets SDS E 4 ...
Page 80: ...Appendix E Safety Data Sheets SDS E 5 E 1 Magnesium Perchlorate ...
Page 81: ...Appendix E Safety Data Sheets SDS E 6 ...
Page 82: ...Appendix E Safety Data Sheets SDS E 7 ...
Page 83: ...Appendix E Safety Data Sheets SDS E 8 ...
Page 84: ...Appendix E Safety Data Sheets SDS E 9 ...
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Page 87: ...Appendix E Safety Data Sheets SDS E 12 E 2 Decarbite ...
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Page 91: ...Appendix E Safety Data Sheets SDS E 16 ...
Page 92: ...F 1 Appendix F Packing Information F 1 EC150 GH Packing Information ...
Page 93: ...Appendix F Packing Information F 2 F 2 EC150 SH Packing Information ...
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