GP2 Data Logger and Controller

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Testimonials

"Working with Delta‐T Devices, we installed two arrays of SM150T soil moisture sensors at varying depths ‐ in selected well‐managed plantations in the Santa Marta region of Colombia. We also installed a WS‐GP2 Weather Station (based around the GP2 Advanced Data Logger and Controller) to provide input data to drive our irrigation model ‐ as there is limited agrometeorological recording in the region. The Delta‐T Devices kit has been first class ‐ it has not missed a beat since we installed the equipment." Prof Jerry Knox
Cranfield Water Science Institute,
Cranfield University, UK
"A major advantage of the GP2 Data Logger is that up to 12 moisture sensors can be monitored concurrently. This enables us to easily position multiple sensors in strategic locations across the cropping area - to help account for the inherent variability in soft fruit growing systems." Mike Davies, Science Project Leader
NIAB EMR (East Malling Research)
  • Powerful and rugged field data logger
  • SDI-12 enabled
  • 12 differential channels
  • Ideal for demanding research applications
  • Compatible with DeltaLINK-Cloud online data sharing platform
  • Calculation of full Penman-Monteith evapotranspiration equation

The GP2 is a powerful 12 channel data logger that is easy to use, versatile, rugged and reliable. It can log most sensor types and accepts voltage, resistance, current, potentiometer, bridge, counter, frequency, and digital state inputs. DeltaLINK software helps the user set up logging sequences and provides control over reading frequency, sensor type, thresholds, units and much more. All Delta-T sensors can be selected from a menu.

 

DeltaLINK‐Cloud – online data viewing and sharing platform

SDI‐12 enabled

GP2 Q&A

GP2 Resource Centre

The Resource Centre contains a wide range of application information and tutorials – covering irrigation control, evapotranspiration, vapour pressure deficit, and much more. Visit the GP2 Resource Centre.

Power and flexibility

The GP2 Data Logger features advanced controller functionality, and sophisticated programs can be easily created via a simple scripting editor.

Click here to learn more about the advanced features of the GP2.

As the user’s needs change, the GP2 can adapt. An optional lid is available for additional cable entry points, or wider diameter cable entry points.

Building systems with the GP2 Data Logger

The GP2 is the ideal data logger for field work, with applications ranging from agronomy, meteorology and hydrology to eco-physiology and soil science. We can supply complete systems including sensors, enclosures, solar power and communications options.

The GP2 Data Logger is compatible with all Delta-T sensors. For the Delta-T WET Sensor there is a dedicated input channel.

Delta-T has decades of experience of instrumentation for environmental research and can advise on all aspects of system specification.

Sensors

The GP2 Data Logger can log most sensor types and accepts voltage, resistance, current, potentiometer, counter, frequency, and digital state inputs.

The GP2’s analog inputs can be fully customised. Each channel can have its own input type and recording parameters. DeltaLINK software gives the user control over reading frequency, thresholds and units, and provides statistical recording options for Average, Minimum, Maximum, Standard Deviation and more. Specialised wind options are available including wind rose, gusts and wind averaging.

Users can add their own custom sensor types to the sensor library, exploiting the GP2’s detailed configuration options. The GP2 provides 4 input ranges down to microvolt resolution with adaptive auto-ranging, excellent analog accuracy, and configurable sensor excitation – enabling it to support nearly all analog sensors.

Calculations based on the measurements from several input channels can be recorded and displayed as additional virtual channels (calculated measurements).

Ease of use

Simple point and click software makes it easy to configure channel set-up and recording intervals. The menus that support the advanced customisation options can be displayed or hidden as required.

Sensor connections are laid out logically with clear, easy-to-follow diagrams and notes.

The GP2’s weatherproof case, battery power and convenient accessories make it very easy to install in the field – often without the need for a secondary enclosure.

Simulator

This unique software feature allows logging programs to be tested before real-world activation. For applications involving weather data, irrigation or soil moisture recording, the environmental variables can be changed to test how the program responds. Years of logging time can be simulated in just a few minutes.

Storage, communications and power

4 MB of FLASH memory enable storage of 2.5 million readings (typical). Data can be collected by a laptop locally via USB/RS232 or remotely using the cellular modem options.

The GP2 has 6 alkaline AA internal batteries as standard. An optional mains power adapter is available (type GP2-PSU). Up to 7 GP2s can share power and communications using an M12 cabling network. GP1 Data Loggers can be integrated into such a network via an adapter cable.

For external battery power options please enquire at sales@delta-t.co.uk

SDI-12 enabled

The GP2 Data Logger supports SDI-12 inputs as standard. GP2s supplied before March 2016 can be easily updated via a software download.

Key features:

  • Huge additional input capacity for SDI-12 sensors
  • Analogue and digital channels fully available
  • Highly flexible logger + sensor networks

For more information visit our GP2 SDI-12 page.

Calculation of full ASCE/FAO 56 Penman-Monteith evapotranspiration equation

The GP2 Data Logger and DeltaLINK software (versions 3.7 and later), in combination with relevant sensors, enables the full ASCE/FAO-56 Penman-Monteith equation for calculating reference evapotranspiration (ETo).

ETo is calculated by the GP2 Data Logger using the available measurements of relative humidity, wind speed, solar radiation, and air temperature. This ET implementation includes the ability to vary crop albedo/LAI, canopy resistances, crop height and sensor heights.

The functionality can be easily accessed by users as a selectable recording option within DeltaLINK. Calculated ET can be recorded as hourly and daily values – and may be used in further bespoke calculations or to guide field irrigation decisions.

User guide to Penman-Monteith Evapotranspiration in the GP2 Logger.

This enhancement also applies to the WS-GP2 Weather Station – an advanced research-grade system.

Applications

The GP2 Data Logger has a wide range of environmental, agricultural and industrial applications: Horticulture and Irrigation, Soil Science, Plant Physiology, Agronomy Climate Research and Meteorology, Agriculture, Turf and Gardens, Amenity Landscaping, Ecology, Field Trials, Eco-Physiology.

View Advanced Details

 

 

Specification

Input connections

12 differential (or 24 single-ended) analog inputs configurable as: Voltage, Resistance (12 3-wire or 24 2-wire), Bridge (12), Potentiometer (12)

4 digital inputs as: Counters, (2 fast + 2 slow), Frequency, Digital state

1 Delta-T WET sensor channel
Unlimited virtual channels

Serial input channel: 62 SDI-12 sensors or a single WET Sensor

Control outputs 2 relay outputs expandable to 6 (1 A)
Readings stored 2.5 Million
Recording rate 1 second to >24 hours
Configuration DeltaLINK
Communication options SDI-12, USB, RS232, ethernet or modem
Sensor excitation Calibrated 3 V reference, +5 V and +12 V regulated, or 5 to 10.5 V (battery or external power), user selectable
Power 6 AA alkaline batteries or external power 10-15 V DC
Battery life (dependent on usage) >310K readings, lasting 530 days
Enclosure rating IP65
Temperature range -20 to +60°C
Display
Size 225 x 185 x 75 mm
Typical applications Demanding research projects
Environmental monitoring
Varied control applications

 

Sensor compatibility (maximum number of sensors that could be connected [1]
ML3 ✓ (6) with temp / (12) without temp
SM150T ✓(6) with temp / (12) without temp
PR2 ✓(2 PR2/6) (3 PR2/4)
PR2 SDI-12 ✓ (50) PR2/6
✓ (62) PR2/4
WET Sensor ✓ (1)
EQ3 ✓ 6 with temp / 12 without temp
Temperature ✓ (12)
Tensiometers ✓ (12)
Counters or Events ✓ (4) 2 fast 2 slow
Relay Output ✓(2) expandable to (6)

 

[1] With appropriate expansion cards and power supply arrangements

 

For full GP2 specification please see the GP2 data sheet

Product Resources

Additional resources can be found at the GP2 and DeltaLINK Resource Centre. The Resource Centre contains a wide range of application information and tutorials – covering irrigation control, evapotranspiration, vapour pressure deficit, and much more.

Data Sheets

Case Studies

Manuals

FAQs

Technical Notes

Advanced features of the new GP2 Data Logger and Controller

  • Powerful, yet highly accessible Script Editor
  • Virtual Channels
  • Unique Simulator function
  • Smart irrigation and fertigation
  • PID control
  • Model implementation, simulation and evaluation
  • Evapotranspiration calculation and analysis

Customised control (simple or advanced)

Control conditions for experiments and applications can range from simple thresholding to sophisticated calculations using the Script Editor. Control parameters (e.g. target soil moisture level) can be adjusted without interrupting data logging.

Script Editor

The GP2 is a flexible and powerful research and control instrument – enabling model implementation, simulation and evaluation. The new Script Editor is easy to use, yet allows the creation of complex functions such as disease prediction, degree days, dew point, wind chill factor, PID control, and evapotranspiration calculation and analysis.

  • Script Editor creates sequences of operations to implement models
  • Advanced control and recording capabilities
  • Easy user interface: no typing out of commands; no programming language
  • Implement simple or complex conditions, algebraic expressions and record result values
  • Create and manipulate variables e.g. for disease risk factor

This powerful software feature creates step by step operations to control simple or complex processes or recording requirements. The editor interface is easy to use – no programming language is involved. It can also implement models, useful in areas such as disease prediction or multi-zone irrigation. This degree of sophistication, including the ability to apply PID control, means the potential applications are numerous and varied.

Virtual channels

Calculations based on the measurements from several input channels can be recorded and displayed as additional “virtual channels”.

Simulator

  • Test and optimise logging programs using the built-in Simulator.
  • Simulate how the program responds to changes in weather data, irrigation systems and soil moisture movement etc.

This unique software feature allows logging programs to be tested before real-world activation. For applications involving weather data, irrigation or soil moisture recording, the environmental variables can be changed to test how the program responds. Years of logging time can be simulated in just a few minutes.

Typical examples of advanced control and modelling

PID ControlThe GP2 is a powerful research tool for experimental research. The powerful new Script Editorfunction gives the user an accessible way to create sophisticated mathematical functions and models that can be applied in real-time to the measurement data collected by the GP2. In experimental work detailed here we have created an enhanced PID controller within the DeltaLINK 3.0 Script Editor – enabling the GP2 to deliver precision irrigation control for a Poinsettia plant. The data collected shows precise control of soil moisture levels and the PID controller responding appropriately to the diurnal cycle. The experimental system also includes water flow and radiation sensors. The GP2 collects data from these sensors and calculates daily totals enabling the relationship between solar radiation and water use to be investigated.

Download GP2 PID scientific poster here.
Explanation of PID Control

(With reference to information below, please note that, as of Sept 2018, the GP2 now also calculates the full FAO 56 / ASCE Penman Monteith equation – see GP2 overview page for more details.)

Evapotranspiration calculation and analysis In this example, the GP2’s Script Editor & Simulator features were used for a comparison of four empirical potential evapotranspiration equations (PET). The Script Editor was used to implement mathematical models (Xu & Singh 2001) that calculated daily average values for air temperature, relative humidity, and solar radiation. These values were then used with empirical models to estimate PET. The results indicate that the solar radiation based models are well grouped and follow a similar trend, whereas the temperature based model (McCloud) appears to overestimate PET.

The empirical PET models described in the poster can be installed into a standard GP2, and with the appropriate sensors, used to calculate real-time estimates of PET. If comparison pan evaporation or lysimeter data is available then the model coefficients can be adjusted on the GP2 to optimise the model for local conditions as outlined by Xu & Singh (2001).

Download GP2 Evapotranspiration scientific poster here.

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