EOLO: the new frontier of boardable dataloggers

EOLO is an embedded data logger for data acquisition from sensors, communication with ECU (Electronic Control Units), data transmission in telemetry, GPS positioning.

The challenge:

Create a ship-based data acquisition system capable of integrating software and hardware modularity, resistance to adverse conditions, wireless telemetry, real-time monitoring and configuration, and GPS data reception in a single product.

The solution:

Use of the NI CompactRIO (cRIO) and NI Compact FieldPoint (cFP) platforms as modular and configurable data acquisition units. Use of high-class PDA devices for monitoring in adverse conditions. Software development for different targets, modular, flexible, adopting NI LabVIEW Real-Time, NI LabVIEW FPGA and NI LabVIEW PDA for development.

The EOLO cRP board-mounted datalogger is designed for use in numerous application sectors, with particular reference to the automotive sector. EOLO cRP is the result of the integration of hardware and software technologies ranging from the Reconfigurable Input Output (RIO) concept to the GPRS wireless telemetry to the programming on the Real-Time operating system. The system hardware consists of off-the-shelf components and stands out for its total modularity; which makes it possible to adapt a single instrument to different measurement needs simply by going through a software configuration phase. The software suite consists of applications for the Real-Time acquisition unit, the PDA monitoring unit and the personal computer for the configuration and reception of telemetry data.

System requirements

The EOLO datalogger stems from the ambitious project of creating an embeddable data acquisition system capable of combining performance, versatility, ease of use and telecommunications capabilities in a single product. EOLO is proposed as a cutting-edge solution for the automotive market but not only, given its versatile, modular, configurable nature.

As will be explained in more detail below, the requirements that the data logger EOLO meets in all its forms are: robustness and compact form factor, acquisition and conditioning signals from various sensors with on board connectivity, hardware modularity, data acquisition on bus CAN. In its most advanced form EOLO is also able to perform wireless telemetry via GPRS and data acquisition with integrated GPS receiver. EOLO has been developed for use both in headless mode (black box) and in connection with an external monitoring unit.

Hardware Architecture

EOLO is proposed, on choice, on two separate hardware acquisition and signal conditioning platforms: CompactRIO (cRIO) and Compact FieldPoint (cFP). The choice between one platform and another strongly determines the characteristics and performance of the system. The cFP platform is privileged where a high number of channels and a boosted modularity are required (ie a frequent and rapid change of acquisition modules), the compactness requirements are not pressing and the sampling frequencies required do not exceed 100 Hz. On the other hand, the cRIO platform has a more attractive form factor and the ability to acquire very high-frequency data (100 kS / s), with the additional possibility of integrating a GSM / GPRS modem and a GPS receiver. In the chassis the platform also includes a reconfigurable 3M gate FPGA, and therefore allows to develop custom hardware in all respects.

EOLO reflects the acquisition and conditioning capabilities of Compact FieldPoint and CompactRIO products; and is therefore compatible with a variety of sensors such as thermocouples, resistance thermometers, strain gauges, load cells and accelerometers. Modules for counter inputs and digital lines are available.

The Real-Time processor of the monitoring unit is equipped with an Ethernet port and one or four serial ports, respectively for Compact FieldPoint and CompactRIO, to allow communication via TCP / IP or serial protocols with monitoring units or with instrumentation external, in the case of custom solutions.

The communication on the CAN bus, in the case of the Compact FieldPoint solution, is managed with the aid of an external CAN / RS-232 conversion board, mounted specifically on the Compact FieldPoint; for the CompactRIO, the CAN NI-9853 module is used with two high-speed ports.

The combined monitoring unit (on request) to the acquisition unit (both CompactRIO and Compact FieldPoint) can be selected from two very high-quality Personal Digital Assistants (PDAs) produced by DAP Technologies. The PDA Microflex CE 8800 is equipped with a 7.2 "touch-screen (resolution 640 x 480) and is proposed for the needs of displaying pushes (up to 32 channels simultaneously in numerical mode and 8 in graphics mode) .This PDA also offers two slots PCMCIA to integrate additional features (such as WiFi), 1 Ethernet port and up to 4 serial ports The second type of handheld is Microflex 2240, which has a more compact form factor while maintaining the same robustness of the CE 8800 (IP67). Microflex 2240 is particularly suitable for those situations where the available space is scarce and it is sufficient to visualize only a few channels at the same time Microflex 2240 has an RS-232 serial port and a USB port, as well as two slots for CompactFlash.

Architecture and functionality of the software

The system software suite consists of a module for the Real-Time acquisition unit, one for the monitoring unit, and one for the PC for receiving telemetry data.

The Real-Time software module (CompactRIO or Compact FieldPoint) is developed in LabVIEW Real-Time. In the case of the Compact FieldPoint platform, the application uses FieldPoint drivers for data acquisition from the installed analog and / or digital input modules, and the low-level configuration of the Compact FieldPoint bank is performed in the Measurement and Automation Explorer environment. In the case of the CompactRIO platform, the FPGA is programmed according to the modules physically present using the LabVIEW FPGA and the transmission to the Real-Time controller of the data acquired from the field takes place on a PCI bus. In order to ensure compatibility with the different hardware configurations, different bitstreams are provided for the FPGA, which can be downloaded to the unit simply via FTP.

The embedded application carries out a series of functions of considerable added value: application of both tabular and polynomial engineering scales; assignment of logical names to physical channels and definition of units of measurement; memorization and definition of custom system setups that can be recalled at any time according to the test needs; definition of trigger channels for the beginning and the end of the acquisition; management of two parallel acquisition loops, one with high frequency for fast signals and one with low frequency for slowly variable signals (such as thermocouples) in order to optimize the overall performance of the system; transmission on request, via Ethernet TCP / IP or serial RS-232, of data to the monitoring unit; transmission via GPRS in real time of the data acquired to a central server; GPS data reception.

The software application for monitoring units is developed in LabVIEW PDA. Using TCP / IP over Ethernet or RS-232 communication, the PDA receives the list of names and units of measurement of the active channels on the acquisition unit and their value in real time, making it available in numerical and / or graphic format .

The data logger configuration in terms of logical names, engineering scales and setup recall, is performed by PC interfacing with the embedded application through a Web Browser. Telemetry data reception is carried out by a specially developed module that, in addition to receiving and displaying data in real time, can recover recorded files.

Advantages of the solution with NI products

The use of a common software platform able to manage different targets such as a Real-Time processor (both on Compact-FieldPoint and on CompactRIO) and an FPGA, has allowed to significantly reduce the development time in parallel of the two versions of the product . The modularity of the hardware characteristic of NI has allowed us to offer the added value typical of an open solution, which the end user is generally looking for. Furthermore, the availability of the combined GSM / GPRS / GPS module developed by third parties for the CompactRIO platform has made it possible to integrate GPS telemetry and positioning in a simple, cost-effective way, maintaining a compact form factor and without losing modularity.

L. Pasquini - EURINS
S. Vianelli - EURINS

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