Soil Moisture Sensor SMT100 Truebner

The of TRUEBNER developed and manufactured SMT100 combines the advantages of a cheap FDR sensor with the accuracy of a TDR measurement. As with a TDR, the dielectric constant of the ground is determined from the signal propagation time and, as with FDR, this is converted into an easily measurable frequency. In contrast to FDR, a capacity is not simply determined, but the transit time is converted into a frequency via a ring oscillator. The resulting frequency (>100 MHz) is high enough so that measurements can also be taken in clayey soil.

Compact, functional and robust: The glass fiber reinforced circuit board enables a cost-effective design and easy installation thanks to the blade shape. The housing and cable are waterproof. Different communication protocols are available as well as a version with analogue output.

The SMT has a large measuring range. It is maintenance-free and frost-resistant. With its short measuring time and the low influence of salinity, it is suitable for continuous use.

Specifications

Downloads:
SMT100_Flyer_A4_english
SMT100_Flyer_A4_english

NEW: SMT100 4-20mA: Replacement for the MAS-1

Note: To operate on OpenSprinkler 3.x you need either:
a) das “Analog Sensor Board” and the variant “Analog 0-3V” or
b) one “RS485 Modbus to TCP Converter” and the “RS485 Modbus” variant
c) for a simple yes/no circuit, the A2D adapter and the variant “Analog 0-3V” or “Analog 0-10V” (+12V power supply)

For the OSPi There are two options, depending on the version:
a) If the analog interface is soldered onto the board, then it can be connected in the “Analog 0-3V” variant or
b) Via the A2D adapter as in c)
In general we recommend for the OpenSprinkler or OSPi the material moisture meter shows you the SMT50

When using the A2D adapter, the actual humidity cannot be logged, this is only possible with it “Analog Sensor Board” or at OSPi via the analog inputs

Hint 2: NEW! With software version 2.3.0 (with Analog Sensor Api), the SMT100 RS485 Modbus can be integrated via the network via a Modbus RTU TCP adapter. See details here.
Alternatively, via this Analog sensor board the analog version 0..3V of the SMT100 can be connected.

Note 3: The “Analog Individual” variant allows you to define the range of the analog output voltage. Since the power supply must be at least 4V, this is the lowest value. Inquire about the desired area beforehand.

Note 4: The protocols of the RS485 variants can be changed by software, the analogue versions only by the manufacturer.