Section 4. Sensor Support
46
4.6 SDI-12 Recording
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SDI-12 Sensor Support
p. 112 and
Serial Input / Output
p. 105.
SDI-12 is a communications protocol developed to transmit digital data from
smart sensors to data acquisition units. It is a simple protocol, requiring only a
single communication wire. Typically, the data acquisition unit also supplies
power (12V and ground) to the SDI-12 sensor. The CR200(X) is equipped with
1 SDI-12 channel and an SDI12Recorder () CRBASIC instruction.
4.7 Cabling Effects on Measurements
Sensor cabling can have significant effects on sensor response and accuracy.
This is usually only a concern with sensors acquired from manufacturers other
than Campbell Scientific. Campbell Scientific sensors are engineered for
optimal performance with factory installed cables.
4.7.1
Analog Sensor Cables
Cable length in analog sensors is most likely to affect the signal settling time.
For more information, see Signal Settling Time.
4.7.2
Pulse Sensors
Because of the long interval between switch closures in tipping bucket rain
gages, appreciable capacitance can build up between wires in long cables. A
built up charge can cause arcing when the switch closes, shortening switch life.
As shown in
FIGURE. Current Limiting Resistor in a Rain Gage Circuit
(p. 46),
a 100 ohm resistor is connected in series at the switch to prevents arcing. This
resistor is installed on all rain gages currently sold by Campbell Scientific.
Figure 32: Current Limiting Resistor in a Tipping Bucket Rain Gage
Circuit
Summary of Contents for CR200
Page 32: ...Section 2 Quickstart Tutorial 22 ...
Page 45: ...Section 3 Overview 35 3 3 Specifications ...
Page 46: ...Section 3 Overview 36 ...
Page 58: ...Section 4 Sensor Support 48 ...
Page 62: ...Section 5 Measurement and Control Peripherals 52 ...
Page 78: ...Section 8 CR200 X Configuration 68 ...
Page 102: ...Section 9 Programming 92 ...
Page 138: ...Section 11 Programming Resource Library 128 ...
Page 156: ...Section 16 Support Software 146 ...
Page 160: ...Section 17 Care and Maintenance 150 ...
Page 167: ...Section 18 Troubleshooting 157 18 3 3 2 Charging Circuit Test Solar Panel ...
Page 168: ...Section 18 Troubleshooting 158 18 3 3 3 Charging Circuit Test Transformer ...
Page 169: ...Section 18 Troubleshooting 159 18 3 3 4 Adjusting Charging Circuit Voltage ...
Page 170: ...Section 18 Troubleshooting 160 ...
Page 184: ...Appendix A Glossary 14 ...
Page 190: ...Appendix B Status Table and Settings 20 ...
Page 192: ...Appendix C Serial Port Pin Outs 22 ...
Page 211: ......