1. Dataloggers

2. Records voltage, current, or circuit closing Environmental variables must be converted to electronic signal

3. Dataloggers Common loggers in Hydro Science –Campbell –Hobo –Many others

4. Campbell CR10X, 800, 1000 Loggernet software Review Components –Analog voltage input Single ended – Voltage measured relative to AG Differential – Voltage on H measured relative to voltage on L (page 7-3) –Power 12V supply, G, Earth Ground 12V out 5V out Sw12V out

5. Campbell CR10X, 800, 1000 Components –Pulse inputs Counts circuit closing –Control ports Digital in and out Most commonly used to turn things on and off Can be programmed as a digital input –Excitation outputs Supplies a specified voltage

6. Campbell CR10X, 800, 1000 Memory –Flash EEPROM stores operating system and programs –SRAM stores data and runs program Data storage –Input storage – temporarily stores measurement or calculation results –Intermediate storage – used by the logger to move things around –Final storage – data stored for transfer (62,000 locations)

7. Campbell CR10X, 800, 1000 Programming sequence (table) (see OV-9) –Execute table –Measure (chapters 9-12 Excite sensor with appropriate delays (if needed) Measure voltage Store input Check –Output processing

8. Campbell Files

9. Sample Program Thermistor measurement –Demonstrate single sensor through output Thermistor.csi –Modify program from 2 thermistors Illustrate sequential memory locations Illustrate loops for calculations –Modify program for a thermocouple

10. Multiplexor Enables multiple sensors per input channel –Repeat measurements of the input channel –Mechanical switching of “sets” between measurements Connections –CLK – Resets to open, no sets connected –RES – Advances the connected set by 1 –COM – Common port connected each set to datalogger

11. More Instrumentation Vocabulary Communication Protocol – How is information (signal) transferred from sensor to logger? http://www.lammertbies.nl/comm/cable/RS -232.html#pins –Analog to digital conversion –Serial (RS232, RS422, RS485) –SDI 12 –USB

12. Analog Sensor –Digital Conversion Analog –Continuous, time varying transmission Thermocouple generates an continuous analog voltage –Volt meter “samples” the continuous signal by a variety of methods to generate a discrete, digital output –CR10x analog inputs convert to digital memory

13. Digital Sensor Sensor contains microchip with internal A/D converter –Signal transmitted digitally Logger receives a series of numbers, rather than raw voltages –CR10X control ports can be used as digital inputs

14. Digital Sensor Serial (RS232, 422, 485) –Different protocols (rules) for transmitting digital information

15. Digital Sensor SDI 12 –Developed by USGS http://www.sdi-12.org/ Becoming standard for environmental sensors Sensor delivers a “string” of numbers Sensor must be given an address

16. Stevens Hydraprobe http://www.stevenswater.com/catalog/stev ensProduct.aspx?SKU='93640'