Campbell Scientific EC150 CO2 and H2O Open-Path Gas Analyzer and EC100 Electronics with Optional CSAT3A 3D Sonic Anemometer - Manual (Page 14)

EC150 CO
2
/H
2
O Open-Path Gas Analyzer
4.6 EC100 Electronics Module
The EC100 electronics module (shown in FIGURE 4-1) controls the EC150
and optional CSAT3A sonic anemometer head. The EC100 synchronizes
measurements and processes data from the EC150 and the CSAT3A.
FIGURE 4-1. EC100 electronics module
4.6.1 EC100 Communications and Control
The EC100 supports several serial communication interfaces, including USB,
RS-485, and Synchronous Device for Measurement (SDM). SDM is a
Campbell Scientific communication protocol that allows synchronized
measurement and rapid communication between a Campbell Scientific
datalogger and multiple devices including the EC150. Although nearly all
Campbell Scientific dataloggers support SDM, only the CR1000, CR3000, and
CR5000 dataloggers support communications with the EC100 electronics with
the EC100() instruction.
The SDM protocol allows the user to configure and control the analyzer
through CRBasic instructions in the datalogger. For example, in solar-powered
applications with limited daylight, battery power can be conserved by
programming the datalogger to turn off the EC150 at night or when conditions
are not suitable for eddy-covariance measurements. The datalogger can also be
used to change settings such as bandwidth, and perform the zero/span
procedure in the field.
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 C,
Alternate EC100 Outputs, for USB, RS-485, and analog outputs.
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