GP2 Data Logger – Questions and Answers


In 2013 Karl Kühn, Principle Software Engineer at Delta-T Devices was interviewed by

AZoSensors – Delta-T has recently launched the new GP2 Data logger and Controller. What has been the main inspiration behind the development of this tool?

KK – Our aim at Delta-T Devices is to develop innovative, robust, and accurate research-grade instruments – that are easy to use. The GP2 Data Logger and Controller falls neatly into this category. It is a very flexible, reliable and feature-rich product, with a strong focus on the ease of use. We have spent a lot of time developing a new system that is intuitive, yet very capable.  It allows researchers to achieve sophisticated results without the need for programming language experience.

AZoSensors – What are the GP2’s key innovative features?

KK – In addition to being a high precision, 12 channel, low power data logger, the GP2 has exceptional control capabilities. It can provide up to 6 output relays – allowing the user to control up to 6 experiments simultaneously – using just one logger. However, even more innovative is the way in which it allows users to easily define their own algorithms and formulae (from simple additions to complex polynomials and more). This, combined with the ability to define custom rules for the controlling of experiments and being able to define scripts for implementing a multitude of models and systems (such as a PID controller or vapour pressure deficit calculations), makes it a very capable logger.

Clever design of the software (DeltaLINK) makes these sophisticated features very accessible to the user and unusually easy to work with.

Another important way in which the GP2 innovates is the DeltaLINK software’s inclusion of a unique full environmental Simulator. This feature allows users to generate realistic simulated environmental data quickly and easily for evaluating their models as demonstrated in figure 1 below.

Years of logging time can be simulated in just a few minutes – enabling researchers to test logging/control programs, and assess results, before real‐world activation.  It removes the risk of researchers wiring up experiments and waiting months only to find out that an algorithm is erroneous.

The Simulator function can be used without any cost, as it works entirely within the DeltaLINK software – which can be downloaded free from the GP2 Resources web page.


AZoSensors – How do other data logging devices differ to the GP2 control system in terms of the levels of sophistication and data collection and analysis?

KK – The vast majority of data loggers available in the market do not have advanced control capabilities, and those that do require in-depth knowledge and understanding of how to write a programming code (or are very limited in their capabilities). This is where the GP2/DeltaLINK combination really stands out.

It provides the user with a very powerful and flexible algorithm, logical expression and script editing interface that clearly guides the user in the creative process. Anybody with a basic understanding of algorithms and logical conditions will be able to create and implement a wide range of models, controller, algorithms and more (examples of what is possible can be seen on our GP2 Resources web page). This functionality combined with the Simulator make the GP2 and DeltaLINK a powerful tool for anybody wanting to implement novel ideas and models as well as those wanting to fulfil a complex requirement with relative ease.


AZoSensors – Exactly how does this new data logger and controller collect data and how is this presented to the end-user?

KK – The GP2 Data Logger and Controller has a comprehensive range of analogue and digital inputs that allow it to take accurate measurements of the connected sensors. These measurements are then stored safely in memory for retrieval later. Using DeltaLINK, which is our free-to download PC software for interfacing with these devices, the customers can download all recorded data and display it graphically (as charts) or in a table.

The user can also download and save the data directly to standard formats such as CSV using a command line tool. These files can then be imported and manipulated in programs such as Microsoft Excel.

AZoSensors – How will the application of the GP2 Data Logger and Controller benefit the end-user?

KK – Due to the flexibility of the GP2 the possibilities for use and benefit are similarly open-ended.  However the GP2’s benefits can be broken roughly into three core areas:

Firstly, its multi-zone functionality – enabling users to control and monitor up 6 independent experiments/zones concurrently.

Secondly, its sophisticated control algorithms – allowing users to create complex and powerful models such as PID (proportional-integral-derivative) Control.

Thirdly, its custom inline data processing – enabling the easy implementation of real-time data driven calculations such as dew-point, wind chill factor and evapotranspiration calculation and analysis.

The benefits of using the GP2 also extend to the attentive and friendly technical support that Delta-T Devices offers by default. We frequently get very positive feedback from customers regarding the quality of technical assistance we provide on our products, often many years after purchase.

AZoSensors – What type of programs can be created with the application of the GP2 Logger and for what purpose?

KK – The range of applications and programs that the GP2 can be applied to are very diverse and really only limited by the imagination and requirements of the user.

What has been really gratifying for us is to see application engineers and customers using the GP2 for implementing models and systems we never even considered when we were designing the instrument. This validates our original goal, namely to create a logger that provides the user with a tool to implement their models and ideas – and deals equally well with basic applications as it does with highly complex applications such as fertigation control, deficit irrigation, Evapotranspiration, PID controllers, water management, land slip monitoring, and others – that have not yet been realised.


AZoSensors – What type of logging programs can be tested using GP2 prior to their implementation into a real-world setting and what environmental data is simulated from this?

KK – Our unique software Simulator is modelled on the weather patterns, soil conditions and seasonality seen in a coastal climate we see here in the UK. This presents a powerful tool for the user to test their systems and models before actually implementing in the field. This ability can dramatically speed up the development and implementation phase of a project – as the user can simulate real conditions and responses in a fraction of the time it would normally take (e.g. simulate years of coherent and valuable data in just a few minutes).

The Simulator function allows a researcher to validate their project (algorithms and implementation thereof) – offering a valuable way to create a proof of concept before embarking on the exercise of commissioning a project. A series of video tutorials explaining how to get up and running with the GP2’s DeltaLINK software can be found at the online-GP2 Resource Centre.

AZoSensors – Who is likely to be your target user audience for this technology and the supporting software resourcing centre?

KK – The target market for the GP2 Data logger and Controller consists primarily of researchers, academics, system integrators, consultants, and technically progressive farmers/growers

AZoSensors – Where can we find further information on the GP2 Data logger and controller?

KK – Our website features several sections dedicated to the GP2 and DeltaLINK software – all of these sections (including the Resource Centre) are accessible from the GP2 product page. Alternatively Delta-T Devices can be contacted directly.


About Karl Kühn

Karl has a degree in Computer Engineering and comes from a background in Industrial Energy Metering as well as the Broadcast industry.Since joining Delta-T Devices in 2010 Karl has been a part of the software engineering team working on the GP2 Data Logger and Controller and associated DeltaLINK software.