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6

OPERATION

2.2  CONNECTING

The TEROS 11/12 works seamlessly with METER data loggers. The TEROS 11/12 can 
also be used with other data loggers, such as those from Campbell Scientific, Inc. For 
extensive directions on how to integrate the sensors into third-party loggers, refer to the 

TEROS 11/12 Integrator Guide

.

TEROS 11/12 sensors require an excitation voltage in the range of 4 to 15 VDC and operate 
at a 4 VDC level for data communication. TEROS 11/12 can be integrated using DDI serial or 
SDI-12 protocol. See the 

TEROS 11/12 Integrator Guide

 for details on interfacing with data 

acquisition systems.

TEROS 11/12 sensors come with a 3.5-mm stereo plug connector (

Figure 1

) to facilitate easy 

connection with METER data loggers. TEROS 11/12 sensors may be ordered with stripped 
and tinned wires to facilitate connecting to some third-party loggers (

Section 2.2.2

).

Ground
Data output
Power

Figure 1  Stereo plug connector

The TEROS 11/12 sensor comes standard with a 5-m cable. It may be purchased with custom 
cable lengths for an additional fee (on a per-meter basis). METER has successfully tested 
digital communication on cable lengths up to 1,000 m (3,200 ft). This option eliminates the 
need for splicing the cable (a possible failure point). However, the maximum recommended 
length is 75 m.

2.2.1  CONNECT TO METER LOGGER

The TEROS 11/12 sensor works most efficiently with METER ZENTRA, EM60, and 
Em50 series data loggers. Check the METER 

download webpage

 for the most recent data 

logger firmware. Logger configuration may be done using either ZENTRA Utility (desktop and 
mobile application) or ZENTRA Cloud (web-based application for cell-enabled ZENTRA data 
loggers).
1.  Plug the stereo plug connector into one of the sensor ports on the logger.

2.  Use the appropriate software application to configure the chosen logger port for the 

TEROS 11 or TEROS 12.  
METER data loggers wil automatically recognize TEROS 11/12 sensors.

3.  Set the measurement interval. 

METER data loggers measure the TEROS 11/12 once every minute and return the average 
of the 1-min data across the chosen measurement interval. 

Summary of Contents for TEROS 11

Page 1: ...TEROS 11 12...

Page 2: ...tions 10 3 2 Components 13 3 3 Theory 15 3 3 1 Volumetric Water Content 15 3 3 2 Temperature 15 3 3 3 Electrical Conductivity TEROS 12 Only 15 3 3 4 Converting Bulk EC to Pore EC TEROS 12 Only 15 3 3...

Page 3: ...ii 4 2 Cleaning 19 4 3 Troubleshooting 19 4 4 Customer Support 20 4 5 Terms and Conditions 21 References 22 Index 23...

Page 4: ...iv...

Page 5: ...are accurate tools for monitoring volumetric water content VWC temperature in soil and soilless substrates and EC TEROS 12 only The TEROS 11 12 determines VWC using capacitance frequency domain techn...

Page 6: ...d in Table 1 to set up the TEROS 11 12 and start collecting data For more detailed installation information consult the TEROS Sensors Best Practices Installation Guide Table 1 Installation Tools Neede...

Page 7: ...il moisture measurement Installing the sensor with the body in a horizontal position will provide measurements at a more discreet depth See Measurement volume of METER volumetric water content sensors...

Page 8: ...d cables or disconnected sensors Cabling issues can be caused by many factors such as rodent damage driving over sensor cables tripping over cables not leaving enough cable slack during installation o...

Page 9: ...isadvantage Requires a specialized installation tool that can be rented from METER Trench The trench installation method is best for shallow installations less than 40 cm This requires digging a trenc...

Page 10: ...comes standard with a 5 m cable It may be purchased with custom cable lengths for an additional fee on a per meter basis METER has successfully tested digital communication on cable lengths up to 1 0...

Page 11: ...to the third party logger manual for wiring details Connect the TEROS 11 12 wires to the data logger illustrated in Figure 2 and Figure 3 with the power supply wire brown connected to the excitation...

Page 12: ...r to the pigtail adapter connections using adhesive line heat shrink to ensure the sensor does not become disconnected during use 2 3 COMMUNICATION The TEROS 11 12 sensor communicates using two differ...

Page 13: ...ote Setting SDI 12 addresses on METER digital sensors using Campbell Scientific data loggers and LoggerNet When using the sensor as part of an SDI 12 bus excite the sensors continuously to avoid issue...

Page 14: ...ate the necessary ranges for most substrates Resolution 0 001 m3 m3 Accuracy Generic calibration 0 03 m3 m3 typical in mineral soils that have solution EC 8 dS m Medium specific calibration 0 01 0 02...

Page 15: ...munications protocol Data Logger Compatibility METER ZL6 EM60 and Em50 data loggers or any data acquisition system capable of 4 0 to 15 VDC power and serial or SDI 12 communication PHYSICAL SPECIFICAT...

Page 16: ...3 6 V Maximum 3 9 V Digital Input Voltage logic low Minimum 0 3 V Typical 0 0 V Maximum 0 8 V Digital Output Voltage logic high Minimum NA Typical 3 6 V Maximum NA Power Line Slew Rate Minimum 1 0 V m...

Page 17: ...ISO 9001 2015 EM ISO IEC 17050 2010 CE Mark 2014 30 EU and 2011 65 EU EN61326 1 2013 and EN55022 CISPR 22 3 2 COMPONENTS The TEROS 11 12 sensor measures soil moisture temperature and EC TEROS 12 only...

Page 18: ...o the section of cable between the sensor head and the ferrite core as this may influence the measurements The TEROS 11 12 VWC measurement sensitivity is contained within a 1 010 mL volume roughly dep...

Page 19: ...uch as in preferences in the ZENTRA software NOTE Even though the sensor head is white in direct sunlight the temperature measurement may read high Use caution when installing the sensor with the sens...

Page 20: ...oil 20 where Tsoil is the soil temperature C measured by the TEROS 12 Finally b 0 is an offset term loosely representing the dielectric permittivity of the dry soil Hilhorst 2000 recommended that b 0...

Page 21: ...rates this relationship Example A soil is at 0 1 m3 m3 VWC has a pore water EC of 0 7 dS m and a dry bulk density of 1 5 Mg m3 The total porosity of the soil can be calculated using Equation 3 Equatio...

Page 22: ...s a single calibration equation will generally suffice for most mineral soil types with ECs from 0 dS m to 8 dS m saturation extract VWC is given by Equation 5 Equation 5 m3 m3 3 879 10 4 RAW 0 6956 A...

Page 23: ...Rinse the sensor and needles thoroughly with tap or deionized DI water NOTE Do not touch the needles with an ungloved hand or bring them in contact with any source of oil or other nonconducting resid...

Page 24: ...y need to be performed Soils with a bulk EC greater than 10 dS m require substrate specific calibrations Section 4 1 Cable or stereo plug connector failure If a stereo plug connector is damaged or nee...

Page 25: ...on of the problem NOTE For products purchased through a distributor please contact the distributor directly for assistance 4 5 TERMS AND CONDITIONS By using METER instruments and documentation you agr...

Page 26: ...r conductivity sensor Soil Science Society of America Journal 64 6 1922 1925 Topp G Clarke J L Davis and Aa P Annan 1980 Electromagnetic determination of soil water content Measurements in coaxial tra...

Page 27: ...y 15 pore water electrical conductivity 15 16 saturation extract electrical conductivity 16 17 email address 20 F fax number 20 ferrite core about 14 I installation installation tool 2 methods 5 6 bor...

Page 28: ...tions 21 22 theory 15 18 electrical conductivity 15 17 See also electrical conductivity temperature 15 volumetric water content 15 VWC See theory volumetric water content troubleshooting 19 20 V volum...

Page 29: ...Court Pullman WA 99163 T 1 509 332 5600 F 1 509 332 5158 E info metergroup com W metergroup com METER Group AG Mettlacher Stra e 8 81379 M nchen T 49 89 1266520 F 49 89 12665236 E info metergroup de...

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