HydraProbe RS-485 Soil Moisture Sensors User Guide

HydraProbe RS-485 Soil Moisture Sensors

Specifications

• Product: RS-485
• Quick Start Guide
• Professional FW Version 6
• Power Requirements: 9 to 16 VDC (12VDC Ideal)
• Power Consumption: 2.5 mA Idle, 25 mA for 2s Active
• Wiring:
  • Red: + Power Input
  • Black: Ground
  • White: Data inverting Signal Negative (-) A
  • Green: Data non-inverting Signal Positive (+) B
• Communication:
  • Baud Rate: 9600
  • Data Bits: 8
  • Parity: None
  • Stop Bits: 1

Product Usage Instructions

Set up the physical connection

• Connect the devices using the appropriate physical interface.
• Make sure to connect the power input, ground, data inverting signal negative (A), and data non-inverting signal positive (B) correctly.

FAQ

• Q: What is the default address for RS-485 sensors?
• A: The default address is 000.
• Q: How do I configure the RS-485 communication parameters?
• A: You need to set the baud rate, parity, data bits, and stop bits to match the settings of both the master and slave devices. All commands sent must end with a Carriage Return Line Feed pair.
• Q: How can I test the communication between RS-485 devices?
• A: You can test the communication by sending commands and checking the responses between the devices. Make sure to make any necessary adjustments to the application or settings if needed.

Introductions

RS-485 is a serial communication standard. It is commonly used in control systems to communicate between devices over long distances, up to 4,000 ft of cable. RS-485 is reliable and robust over longer distances but it does draw more power than comparable communication protocols such as SDI-12. RS-485 allows for multiple devices to be connected to a single bus. Each device on the bus has a unique address and can be addressed individually or as a group. Different RS-485 sensors may have specific requirements and commands unique to their functionality.
Older versions of HydraProbe firmware may have different commands, contact Stevens Water for more information.

How To Use

Using RS-485 involves setting up a master-slave communication system between devices. The master device (logger) sends requests to the slave device (HydraProbe) to read or write data, and the slave devices respond with the requested data. The basic steps to use RS-485 are below:

1. Set up the physical connection: Connect the devices using the appropriate physical interface.
2. Set up the RS-485 communication parameters: Configure the baud rate, parity, data bits, and stop bits to match the settings of both the master and slave devices. All commands sent must end with a “Carriage Return” and “Line Feed” pair.
3. Assign RS-485 addresses: Assign a unique address to each slave device on the network. Devices can be addressed as a group by using the broadcast address “///” or individually.
4. Follow the instructions for the logger you want to use or develop your RS-485 application: There are different libraries and software tools available to simplify the development of RS-485 applications, depending on the programming language or platform used.
5. Test: Test the communication between the devices and make any necessary adjustments to the application or settings.

Addressing
The first three characters of any command or response on RS-485 is the sensor address. Lowercase ‘aaa’ is used to represent the address. Each RS-485 sensor must have its unique address. The default address is “000”.

Identification

Measurement

Measurement Set 0 or 1

| Read Only

aaaXR_QM

| ****

aaa<X/0>

| Read Quick Mode Selection X – Quick Mode Disabled

0 – Quick Mode Enabled

| ****

Read Only

aaaXW_QM_X| aaaX| Disable Quick Mode| Write Only
aaaXW_QM_0| aaa0| Enable Quick Mode| Write Only

The following tables list the values and units:

(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)
RS485 Measurement Sets

Command| P1| P2| P3| P4| P5| P6| P7| P8| P9
T0, Transmit Set 0| F| I| G| H| J| L| M| K| O
T1, Transmit Set 1| L| M| N| O| P|  |  |  |

Pore Water Offset

Offset>

| Read Pore Water Offset| Read Only
aaaXWPWOS| aaa| Write Pore Water Offset| Write Only
aaaXD_PWOS| aaa+3.4| Reset Pore Water Offset to

default 3.4

| Write Only

Calibration
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.

RS-485 Command| Response| Description| Access

Level

---|---|---|---

aaaXR_SOIL

|

aaa<G/O/R/C/K>

| Get current calibration soil type G – General

O – Organic R – Rockwool

C – Custom 1

|

Read Only

 |  | K – Custom 2|
---|---|---|---

aaaXWSOIL

|

aaa<G/O/R/C/K>

| Write calibration soil type G – General

O – Organic R – Rockwool C – Custom 1

K – Custom 2

|

Write Only

aaaXR_COEFA| aaa| Read coefficient A| Read Only
aaaXR_COEFB| aaa| Read coefficient B| Read Only
aaaXR_COEFC| aaa| Read coefficient C| Read Only
aaaXR_COEFD| aaa| Read coefficient D| Read Only
aaaXR_COEFE| aaa| Read coefficient E| Read Only
aaaXR_COEFF| aaa| Read coefficient F| Read Only
aaaXR_COEF| aaa