Boost Your PLC System: Embedded Data Logging Print E-mail

This article is part of the 7 Ways to Boost Your PLC System white paper series.


 With some applications, you need to not only acquire and analyze the system measurements in real time but also collect and store the data to disk for future use. Should you use an existing programmable logic controller (PLC) or get a separate data logger?

New Technology for Embedded Data Logging

Because PLCs are traditionally not designed for data logging, you may try to bridge this gap by attaching standard computers to the PLCs to take care of data storage. However, this clunky workaround is often difficult to construct, troubleshoot, and maintain due to the challenges that come with incorporating poorly matched hardware and software components.

National Instruments offers NI CompactRIO programmable automation controllers (PACs) to meet your embedded data-logging needs. CompactRIO combines the ruggedness and reliability of the PLC world with the accuracy and high-speed data acquisition of the measurements world. Each system comes with a powerful controller and rugged chassis rated at up to -40 to 70 °C operating temperature, 50 g shock, and 5 g vibration. You can mix and match some of the more than 50 NI C Series I/O modules to create a custom acquisition system that measures temperature, current, pressure, strain, and more.

Figure 1. NI CompactRIO features rugged, high-performance I/O for embedded data logging.

Ideal for stand-alone operation, this compact data logger has onboard nonvolatile storage memory (up to 4 GB) as well as options for removable USB memory devices and SD cards. With the built-in Ethernet and serial ports, you can remotely view real-time data, configure parameters on human machine interfaces (HMIs), and download logged files via FTP. Plus, you can use easy expansion I/O for scaling to high-channel-count systems.

CompactRIO systems are programmed with easy-to-use NI LabVIEW and LabVIEW Real-Time Module graphical tools that include features such as logging, file storage, signal analysis, and decision making. You also have the option of using the LabVIEW FPGA Module to program the field-programmable gate array (FPGA) hardware embedded in CompactRIO. The FPGA can implement custom timing, triggering, and synchronization of I/O signals to customize your data logger and meet unique application requirements.

Case Study: CompactRIO Meteologgers in a Wind SCADA

The Renewable Energy Department in Spain contracted Cosinor S.A. to develop a meteorological acquisition system that was integrated with a wind farm supervisory control and data acquisition (SCADA) system. Various meteorological sensors in each tower required a flexible data logger that could read analog, digital, and pulse train frequency signals. Plus, the data acquisition of the sensors had to be synchronized across multiple towers.

Figure 2. Cosinor used CompactRIO to log meteorological data for a wind SCADA system.

Cosinor chose CompactRIO as a highly configurable data logger that adapts to the different sensors' types and positions as well as store and timestamp the data at regular intervals. A third-party CompactRIO mobile wireless module with GPS capabilities was used to synchronize all the data-logging systems by adjusting acquisition to the GPS startup time. Plus, the CompactRIO FPGA module performed all the period computations to produce a cleaner frequency signal for the real-time processor to use. The ability to distribute computations between the FPGA code and the real-time controller application was an important requirement for Cosinor.

To monitor the meteorological variables in real time and view historical graphs, the SCADA system’s OPC client communicated with the OPC servers on the CompactRIO hardware. Cosinor also created a Web interface to view the status of each data logger individually rather than at the system level. Finally, by using scheduled tasks, Cosinor automatically downloaded the logged files via FTP and stored them on a local server for future access.

Read the full case study

Additional Case Studies

How to Boost Your PLC System

By adding embedded data logging to industrial applications, you can acquire measurements on your system and store the information for future analysis and trending. To address these remote monitoring needs, CompactRIO offers high-performance I/O modules, gigabyte storage memory, and easy connectivity with field and enterprise networks. For more information, refer to the following resources:

 

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