STEVENS HydraProbe SDI-12 Professional FW User Guide
- June 9, 2024
- STEVENS
Table of Contents
SDI-12 Quick Start Guide
Professional FW Version 6.0
HydraProbe SDI-12 Professional FW
SDI-12 communication protocol allows compatible devices to communicate with each other. More information about SDI-12 can be found at http://www.sdi-12.org. 4.1, 4.0, 3.0, 2.8 and 2.7 firmware versions have a different array of commands. Contact Stevens Water for more information.
Model Numbers
Version Part # Suffix
2| Professional, w/25 ft. cable
4| Professional, w/50 ft. cable
6| Professional, w/100 ft. cable
Power
| Power Requirements | 9 to 16 VDC (12VDC Ideal) |
|---|---|
| Power Consumption | <1 mA Idle, 10 mA for 2s Active |
Wiring
| Red Wire | + Power Input |
|---|---|
| Black Wire | Ground |
| Blue Wire | SDI-12 Data Signal |
Addressing
The first character of any command or response on SDI-12 is the sensor
address. A lowercase ‘a’ is used to represent the address. Each SDI-12 sensor
must have its own unique address. The default address is “0”.
Use SDI-12 “Transparent Mode” to issue commands.
| SDI-12 Command | Response | Description |
|---|---|---|
| aAb! | b | Change Sensor Address |
a – Sensor Address
b – New Sensor Address
Identification
A request for identification will return the sensor address, part number, firmware version, sensor version, calibration, and serial number.
| SDI-12 Command | Response | Description |
|---|---|---|
| aI! | a12STEVENSWnnnnnv.vvvcSNxxxxxxxx | Send Identification |
a – Sensor address
12 – SDI-12 protocol version
STEVENSW – Manufacturer
nnnnn – Part number
v.vvv – Firmware version
c – Calibration
xxxxxxxxx – Serial number
Measurements
| SDI-12 Command | Response | Description |
|---|---|---|
| am! | attn. | Request Measurement |
a – Sensor address | Send Measurement Readings The following tables list the values and units: Command| P1| P2| P3| P4| P5| P6| P7| P8| P9 The following extended command will change the coefficients in one of two
general formulas that translate the real dielectric permittivity to soil
moisture. In many cases, the HydraProbe will not need to be recalibrated. The
default General calibration has been heavily reviewed and will provide
reasonable accuracy for most applications. If you need to change the
calibration or if a custom calibration is required, we recommend referring to
the HydraProbe user manual for more information. G – General Parameter| *Accuracy of soil moisture depends on the soil and is highly variable. Read User Manual Online (PDF format) >>
ttt – seconds (000 – 999) until the
measurement is ready
n – number of data fields (1-9) in the
measurement
aD0!| a
F – Soil Moisture
I – Bulk EC (Temp Corrected)
G – Temperature (C)
aD1!| a
H – Temperature (F)
J – Bulk EC
L – Real Dielectric Permittivity
aD2!| a
M – Imaginary Dielectric Permittivity
K – Pore Water EC
O – Dielectric Loss Tangent
aM1!| attn.| Request Measurement
tat – seconds (000 – 999) until the
measurement is ready
n – number of data fields (1-9) in the
measurement
aD0!| a
L – Real Dielectric Permittivity
M – Imaginary Dielectric Permittivity
N – Imaginary Dielectric Permittivity
(Temperature Corrected)
aD1!| a
O – Dielectric Loss Tangent
P – Diode Temperature
Selector Order
Parameter
Unit
F
Soil Moisture
Water fraction by Volume (wave)
G
Soil Temperature
Celsius (C)
H
Soil Temperature
Fahrenheit (F)
I
Bulk EC
(Temperature Corrected)
Siemens/Meter (S/m)
J
Bulk EC
Siemens/Meter (S/m)
K
Pore Water EC
Siemens/Meter (S/m)
L
Real Dielectric Permittivity
–
M
Imaginary Dielectric Permittivity
–
N
Imaginary Dielectric Permittivity
(Temperature corrected)
–
O
Dielectric Loss Tangent
–
P
Diode Temperature
Celsius (C)
SDI-12 Measurement Sets
aM! and aC!| F| I| G| H| J| L| M| K| O
aM1! and aC1!| L| M| N| O| P| | | | Pore Water Offset
SDI-12 Command
Response
Description
aXR_PWOS!
a
Read Pore Water Offset
aXWPWOS
a
Write Pore Water Offset
aXD_PWOS!
a+3.4
Reset Pore Water Offset to default 3.4
Calibration
SDI-12 Command
Response
Description
aXR_SOIL!
a<G/O/R/C/K>
Get Current soil type
O – Organic
R – Rockwool
C – Custom 1
K – Custom 2
aXRSOIL
G – General
O –Organic
R – Rock Wool
C – Custom 1
K – Custom 2
aXR_COEFA!| a| Read coefficient A
aXR_COEFA!| a| Read coefficient B
aXR_COEFA!| a
aXR_COEFA!| a
aXR_COEFA!| a
aXR_COEFF!| a
aXR_COEFF!| a
aXWCOEFA!| a| Write coefficient A
aXWCOEFA!| a| Write coefficient B
aXWCOEFA
aXWCOEFA
aXWCOEFA
aXRCOEFF
aXR_COEFF!| aAccuracy and Ranges
---|---
Soil moisture for inorganic mineral soils| Accuracy*: +/- 0.01 WFV for most
soils ( m3,m-3)
+/- <0.03 for fine textured soil (typical)
Range: From Complete Dry to Full Saturation (0% to 100% of saturation)
Bulk EC| Accuracy: +/- 2.0% or 0.02 S/m Whichever is greater
Range: 0 to 1.0 S/m
Temperature| Accuracy: +/- 0.3 °C
Range: -40 to 75 °C
Inter-Sensor Variability| +/- 0.012 WFV (Typical)
Pore Water EC| Hillforts Equation, depends on soil conditions References
Read User Manual Online (PDF format)
Download This Manual (PDF format)