Hardware and Software Development for the Biogas Industry Accelerated by Using a Flexible Software Framework

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"The DVel approach of only implementing unique functionality and reducing code duplication to virtually zero offers faster development and reduced commissioning time due to reused, well-tested, and production-ready code."

- Roger Isaksson, DVel AB

The Challenge:
Rapid development of hardware and software for the biogas industry, without compromising accuracy and reliability of measurement data.

The Solution:
Basing the solution on DVel's LabQT framework and National Instruments hardware offers faster development and reduced commissioning time due to reused, well-tested, and production-ready code and hardware that let users determine trends on saved data, generates reports, and configures which channels to log.

Author(s):
Roger Isaksson - DVel AB

Swedish-based Bioprocess Control (BPC) is one of the world’s leading manufacturers of biogas production technology. BPC has 15 years of R&D experience in the field and knowledge regarding instrumentation, control, and automation of anaerobic digestion processes. For example, the BPC AMPTS is the de facto industry standard for measuring gas flow from a biochemical methane potential test. BPC strives to optimize and refine the production of biogas by offering lab-scale production equipment in which the researcher or engineer can control and monitor critical properties. Some of these properties are hard to measure accurately, such as the low-volume gas flow from bioreactors.

BPC has entered a long-term commitment to work with DVel, an NI Alliance Partner, because of the company’s extensive experience with most NI platforms. These include DVel’s in-house custom Single-Board RIO add-on PCBs and high-channel-count, off-the-shelf PXI systems and associated CompactDAQ modules. DVel also has broad software experience ranging from large-scale reusable and well-tested object-oriented application frameworks to small, low-level FPGA applications working seamlessly together.                                                                                            

DVel and BPC have jointly produced the uFlow stand-alone logger. We based the system on the cDAQ-9181 1-slot Ethernet chassis, the NI 9203 C Series module, and LabVIEW software. Figure 1 shows the uFlow unit and Figure 2 shows the uFlow logger based on NI products. The uFlow unit connects to the uFlow DAQ logger using a simple electrical interface where the voltage represents the gas flow.

In addition to assisting BPC with product development, DVel also created production measurement and calibration system software for the gas flow meters. After the initial discussion and setting the scope with BPC, DVel decided on an easy-to-maintain object-oriented state machine architecture with an Excel-based front end for loading calibration parameters into the state machine. The reporting after each calibration run generates an Excel file for easy review. Microsoft Excel interoperability simplifies industy-standard document format (XLSX) sharing. Figure 3 shows the calibrator application software front end and Figure 4 shows the calibration setup file.

The high-level software engineering system overview block diagram for the calibrator application can be found below. In this case, we selected a USB-based distributed topology for all I/O communication, which simplified the communication interface to one physical layer. Figure 5 shows a system-level block diagram of the flow meter calibrator.

All software, with the exception for BPC and application-specific code, uses an open source license (LGPL). The particular middleware framework used in most of DVel’s system solutions is LabQT. This framework can be downloaded and integrated in any suitable project. The LabQT software system has been used and has evolved since its introduction in 2009. DVel’s LabVIEW Champion Roger Isaksson and CLD Per Hedlund  currently develop and maintain it. The framework can be found at https://gitorious.org/labqt. Template LabQT projects, both local and distributed variants can also be found at the same site.

LabQT Project Templates

Each of the LabQT and customer-specific code blocks have a clear representation in the LabVIEW implementation on the FPGA, RealTime controller, and host computer. See below for an application entry point VI and a UI handling example. Figure 6 and Figure 7 show the block diagram entry-level VIs.

Usually the separation between customer specifics and LabQT is very distinct. For example, the BPC test system has a specific driver layer for analogue and digital I/O. Specific requirements such as the UI panels and tabs, calibration specification data files, and calibration data processing are all custom made for each system. We use object-oriented I/O-level frameworks, which enables the use of simulated signal and measurement data playback capability. As a typical figure, the system-specific code accounts for about 90 percent of the effort. The remaining effort is spent maintaining and adding new functionality to LabQT.

Results

The DVel approach of only implementing unique functionality and reducing code duplication to virtually zero offers faster development and reduced commissioning time due to reused, well-tested, and production-ready code.

BPC consults DVel on software updates, implementing additional functionality, and internally specifying new systems based on these engineering concepts. At DVel we are proud to help deliver systems exceeding the customer specifications, on time and on budget, to use for the development of the next generation of process and product improvements at BPC. BPC's CEO Dr. Jing Liu asserts: "I have great experience working with DVel for several development projects. The team members have very good competence and wide knowledge in software and hardware development. They are also open minded and flexible to meet specific requirement from both our technical team and our customers. In my opinion, DVel is an excellent technical and business partner for SME.”

Author Information:
Roger Isaksson
DVel AB
Sweden
Tel: +46 733 85 68 59
roger.isaksson@dvel.se

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