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GroPoint Pro!
TECHNICAL INFORMATION
The GroPoint™ Pro soil sensor is robust, reliable and
highly accurate, providing cost-effective
measurement of soil moisture, soil temperature,
salinity (electrical conductivity or EC). This SDI-12
sensor also functions as a wetting front detector,
providing a separate output for the wetting front
measurement. The sleek, light-weight design
installs quickly with minimal soil disruption. When
installed vertically, the sensor averages volumetric
moisture content over a soil layer of about
6” (15cm). When installed horizontally, the sensor
can be used to measure moisture at a specific soil
depth.
Wetting Front!
By placing the tip of the sensor just above the bottom of your crop's root zone, the
wetting front measurement will indicate when water has reached the bottom of the probe
during irrigation, allowing you to have your irrigation stop at precisely the optimal time to
ensure only the water needed is applied.
The GroPoint Pro calculates the first derivative (rate of change) of moisture to indicate
how quickly the moisture level is increasing (it does not indicate in any way moisture
decreases). Range is 0 (very low or negative rate of change) to 10 (high rate of change). A
slow moisture increase generates low values, whereas a very rapid moisture increase
generates higher readings (up to the maximum of 10). It is not related to absolute
moisture level, rather how quickly the moisture level is changing. There is no time
element in this measurement, it just compares previous readings to the current reading.
For example, assuming dry to saturated step change, wetting front readings will appear
similar to this over time:
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GroPoint™ is a division of RioT Technology Corp.
1 833 GRO-POIN (N. America) or 250 412 6642
gropoint.com
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0 (no moisture change)
0 (no moisture change)
1 (minor increase in moisture level)
10 (sudden increase in moisture level)
7 (no moisture change (already at high level) or moisture drops)
4 (no moisture change (already at high level) or moisture drops)
1 (no moisture change (already at high level) or moisture drops)
0 (no moisture change (already at high level) or moisture drops)
Important note: The sensor must be continuously powered to provide useful wetting front
measurement, as it maintains historical data values used in its calculations which are lost
if power is turned off.
Wiring Legend!
SDI-12
Rugged Connector!
Environmental sealing:
• Integral O-Ring gasket
• IP68 seal rating
Materials:
• Connector shell: thermoplastic
⚫︎ Red: DC input voltage
⚪︎ White: SDI-12 I/O
⚫︎ Green: Ground/Common
⚫︎ Black: no connection
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GroPoint™ is a division of RioT Technology Corp.
1 833 GRO-POIN (N. America) or 250 412 6642
gropoint.com
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• Shell interior: Elastomeric
• Contacts: Copper alloy
• Contact plating: Gold over nickel
Mounting procedure:
Align connector, push on, rotate bayonet ring until
tight.
SDI-12 Command Set !
The GroPoint Lite (SDI-12 and RS-485 version) conforms to/implements all aspects of the
SDI-12 V1.3 protocol specification. (a = sensor address).
All other commands received by the sensor will be acknowledged with the device
address only.
Measurement Sequence and Output Format!
Example measurement sequence with sensor address = 3 (SDI-12 logger-issued
commands are in bold, followed by the sensor response):!
Command
Meaning
Response
a!
Acknowledge
Device address (default address is '0')
aI!
Send identification
Identification string
aAb!
Change address
Change device address to ‘b’
?!
Address query
Device address
aM!
Start moisture measurement
Measurement time and count (e.g. “a0026”)
aM1!
Start temperature measurement
Measurement time and count (e.g. “a0023”)
aC!
Start concurrent measurement
Measurement time and count (e.g. “a00206”)
aD0!
Send data
Measurement results
aD1!
Send data
Additional data (if necessary)
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GroPoint™ is a division of RioT Technology Corp.
1 833 GRO-POIN (N. America) or 250 412 6642
gropoint.com
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3M!30024!
3
3D0!3+12.6+1.64+25.8+10.0
In response to the 3D0! command, the sensor address is echoed back, followed by the
volumetric water content in percent (+0.00% to +55.0%), the bulk conductivity in
decisiemens per metre (+0.00 dS/m to +4.00 dS/m), the temperature in degrees Celsius
(-30.0°C to +80.0°C), and finally the wetting front in relative units (+0.00 to +10.0). All data
values are delimited by the + or – symbol.
Identification Output Format!
3I!
313GROPOINTGPPRO113
In response to the 3I! command, the sensor address is echoed back, followed by the
SDI-12 protocol version (1.3 without the dot), the GroPoint identifier (GROPOINT), the
product descriptor (GPPRO), and finally the firmware version (1.1.3 without the dots).
Sensor Start-up Time / Measurement Time!
The time from application of power to the SDI-12 power bus until the sensor is ready to
receive a command is approximately 75ms. The reported measurement time in response
to the aM! measure command (where a is sensor address) is 3 seconds, measured from
the end of aM! command response (a003n<CR><LF>) where n is the number of
segments. Temperature measurements (M1!) always report 2 seconds for measurement
time. Actual measurement times are less, and a service request is issued as soon as the
measurement is completed. Current is at active level (15-20 mA) only during
measurement time, otherwise current is less than 0.1 mA.
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GroPoint™ is a division of RioT Technology Corp.
1 833 GRO-POIN (N. America) or 250 412 6642
gropoint.com
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