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Command 

Function 

Sensor Response 

aCC1! 

aCC9! 

Start Additional 
Concurrent 
Measurement 

 

Request CRC 

a00000<CR><LF> 

No data to be provided

 

 

aD0! 

Get First 4 Data 
Items in 
response to a 
Measurement 
command: VWC, 
Soil Temp., Soil 
Permittivity, Soil 
EC 

 

Get the response 
from a Verify 
command 

a + VVV.V + TT.T + PP.P + EEEE + CCCC<CR><LF> 

where:   a = device address 

              VW.V = volumetric water content % 

              TT.T = soil temperature degrees C 

              PP.P = soil permittivity  

                EEEE = soil bulk EC in µS/cm

 

                CCCC = soil pore water EC in µS/cm 

 

 

Data buffer 
Populated by: 

Command Description 

Response to "aD0!" 

 

none/abort 

 

No data generating command has been issued, or a command was aborted.  Data buffer is 
empty. 

 

a<CR><LF> 

 

 

aM! 

 

Fill data buffer with standard measurement 

 

a+VVV.V+TT.T+PP.P+EEEE +CCCC 
<CR><LF> 
where: 
VVV.V = Volumetric water (%) 
TT.T = Temperature (°C) 
PP.P = Permittivity (no units) 
EEEE = Bulk electrical conductivity 
(

µ

S/cm) 

CCCC = SOIL Pore Water EC 
(

µ

S/cm)

 

 

aC! 

Fill data buffer with standard measurement concurrently with other sensors 

 

Same as aM! 

 

aMC! 

 

Fill data buffer with standard measurement and CRC check in the data response 

 

a+VVV.V+TT.T+PP.P+EEEE+CCCC<C
R><LF> 
where: 
VVV.V = Volumetric water (%) 
TT.T = Temperature (°C) 
PP.P = Permittivity (no units) 
EEEE = Bulk electrical conductivity 
(

µ

S/cm) 

CCCC = Soil Pore Water EC (

µ

S/cm) 

 

 

aCC! 
 

Fill data buffer with standard measurement concurrently with other sensors and with a CRC 
check in the data response 

 

Same data as aMC! 
 

 

aM1! 

Fill data buffer with standard measurements 

 

Same as aM! 

Summary of Contents for TDR Series

Page 1: ...Acclima TDR Sensor User Manual For Sensor Models TDR305H TDR310H TDR315H...

Page 2: ...the medium though which the wave has passed The fact that propagation time is independent of soil electrical conductivity leads to the fact that the calculated permittivity is also independent of soi...

Page 3: ...compacted to avoid air pockets near the waveguide and to prevent the creation of a preferential path for surface water to percolate down to the sensor When the installation is complete the entire soil...

Page 4: ...was developed from the TDR310H as a measurement solution for soils with exceedingly high salt levels It provides credible measurements in soils with saturated paste extraction EC levels up to 20 dS m...

Page 5: ...nsor is connected to This may require the use of a laptop and special software provided by the data recorder manufacturer Connecting the Sensors to the Data Recorder The wiring diagram for the sensor...

Page 6: ...If the data recorder does not supply power to the SDI 12 port then use the diagram below for connecting the sensors...

Page 7: ...ation The sensor ignores unimplemented commands outside those required by the SDI 12 specification There is no response to them Additional Extended Commands that are not enumerated here are incorporat...

Page 8: ...aborted Data buffer is empty a CR LF aM Fill data buffer with standard measurement a VVV V TT T PP P EEEE CCCC CR LF where VVV V Volumetric water TT T Temperature C PP P Permittivity no units EEEE Bul...

Page 9: ...Same as above aV Verify Sensor operation This command produces the same result as the aM Command Same data as aM aD1 aD9 No data for these commands al Send Identification aSSVVVVVVPPPPPPcccxx xx a13A...

Page 10: ...sensor which is then followed by the serial number Making Measurements with the SDI 12 Sensor There are two commands that cause the SDI 12 sensor to take measurements and store them for subsequent re...

Page 11: ...or and the commands used to retrieve them Data Item Request Command Response Example Units Volumetric Water Content aD0 25 0 Soil Temperature aD0 32 1 C Bulk Relative Permittivity aD0 32 1 Soil Electr...

Page 12: ...of seconds that are required to take the readings 001 1 second then finished with the number of data items that will be returned with each measurement request 5 Every response from the sensor is termi...

Page 13: ...uests the five data items exactly in the same manner as with non concurrent readings Data Communication Error Checking So far all Start Measurement commands that we have discussed have requested data...

Page 14: ...for sensor operation The measure error code indicates that a point was reached in the waveform analysis where an unresolvable mathematical condition was reached This would be due to shorted rods or t...

Page 15: ...is desired it is necessary to convert the time ordinate to 5ps units or 220 This number is then converted to hexadecimal 220 decimal 0DC hex If the device address is 1 then the following command is s...

Page 16: ...Reporting Accuracy 0 25 C 0 to 50 C EC Reporting Accuracy 25 S cm 0 to 1 000 S cm BEC 2 5 1 000 S cm to 6 000 S cm BEC Architectural Characteristics Waveguide Length 305H 310H 315H 5 cm 305H 10 cm 310...

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