VSL Voltage Sensing Logger for soil, plant, and environment voltage sensors

The VSL Voltage Sensing Logger is for the measurement of analogue and voltage output sensors commonly used in soil, plant, and environmental monitoring applications. With a self-contained battery, the VSL is able to provide the power for the sensor, as well as record the data from the sensors. Compatible with a range of sensors, the VSL is available in preconfigured packages:

• STM: Soil Tension Meter for multiple measurements of soil water potential using Tensiometers with a pressure transducer
• SMM: Soil Moisture Meter for the measurement of soil moisture at multiple depths to construct a soil moisture profile
• HFM: Heat Flux Meter for the measurement of multiple heat flux plates simultaneous in conjunction with a THERM-Surface sensor.

All VSL packages can be powered by an external 24-volt power supply for laboratory applications, or with a 20W solar panel for field installations.

About the STM

Using the VSL, the STM can support up to 5 tensiometers, providing the ability to measure soil water potential at multiple depths or across an area. These measurements can be used to construct detailed models of plant and tree responses to drought stress or tolerance when combined with a PSY1 Psychrometer.

About the SMM

The SMM uses the VSL in conjunction the MP406 soil moisture sensor. This can be used to measure soil moisture content in soil columns, lysimeters, or for field measurements where multiple depths of soil moisture measurement is required.  The SMM1 can support up to 5 standing wave sensors (MP406 or MP306). With a soil water characteristic curve, the SMM1 can be programmed to simultaneously measure soil water content and soil water potential.

About the HFM

Suited for the measurement of heat flux through built surfaces. Focused on the measurement of insulation (or uninsulated) built structures, the HFM can be used in the calculation of thermal insulation efficiency – the R² or U value.

Instrument Logging
Analogue Channels	5 differential or 10 single ended
Resolution	0.00001V—24-Bit
Accuracy	0.001V
Minimum Logging Interval	1 second
Delayed Start	Suspend Logging, Customised Intervals
Sampling Frequency	10Hz

 

Data
Communications	USB
Data Storage	MicroSD Card, SD, SDHC & SDXC Compatible (FAT32 format)
Software Compatibility	Windows 10
Data File Format	Comma Separated Values (CSV) for compatibility with all software programs

 

Operating Conditions
Temperature Range	-40°C to +80°C
R/H Range	0-100%

POWER
Internal Battery Specifications	960mAh Lithium Polymer, 4.20 Volts fully charged
External Power Requirements
Bus Power	8-30 Volts DC, non-polarised, current draw is 200mA maximum at 17 volts per logger
USB Power	5 Volts DC
Internal Charge Rate
Bus Power	60mA – 200mA Variable internal charge rate, maximum charge rate of 200mA active when the external voltage rises above 16 Volts DC
USB Power	100mA fixed charge rate
Internal Power Management
Fully Charged Battery	4.20 Volts
Low Power Mode	3.60 Volts – Instrument ceases to take measurements
Discharged Battery	2.90 Volts – Instrument automatically switches off at and below this voltage when no external power connected.

Case studies

Downloads and Technical Info

Scripts And Calculations