Top 10 LabVIEW 8.6 Features for CompactRIO Developers
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With the release of the NI LabVIEW Real-Time Module 8.6 comes a host of features for the NI CompactRIO reconfigurable control and acquisition platform designed to reduce development time for advanced control. The following is a snapshot of the top 10 LabVIEW 8.6 features for CompactRIO users.
1) Quick Access to I/O in LabVIEW Real-Time and Host VIs – The new CompactRIO Scan Mode automatically detects your I/O modules and adds them to the LabVIEW Project. You can then drag and drop the I/O variables onto your LabVIEW Real-Time and host VI block diagrams and instantly read and write scaled, calibrated I/O data without any FPGA programming or compiling (see Figure 1).
At a user-specified rate of up to 1 kHz, the NI Scan Engine, a new component of the LabVIEW Real-Time Module, updates the I/O variable values. All channel scans are hardware-timed with module-to-module synchronization. The scan engine also provides a timed-loop timing source, so you can synchronize code with I/O updates for low-jitter control applications.
Figure 1. CompactRIO Scan Mode provides direct access to I/O in LabVIEW Real-Time and host VIs by dragging and dropping I/O variables to your block diagram without requiring FPGA programming.
2) CompactRIO Scan Mode for LabVIEW FPGA – You also can use the new scan mode with the LabVIEW FPGA Module 8.6 on a per-I/O-module basis. To implement custom triggering, hardware-based analysis, signal processing, or high-speed analog streaming, select some modules to be removed from scan mode. Then, use LabVIEW FPGA to program the modules while using I/O variables to read and write I/O on the remaining modules (see Figure 2).
Figure 2. This VI accesses I/O with the new CompactRIO Scan Mode feature while also computing the FFT of an acceleration input with LabVIEW FPGA.
3) Test Panels – The new NI Distributed System Manager provides test panels for CompactRIO modules using the scan mode. When your system is available on the network, you have access to real-time and historical-trend I/O values for quick verification of connections and signal integrity (see Figure 3).
4) Built-In Counter, Quadrature Encoder, and PWM Functionality – The scan mode adds counter, quadrature encoder, and pulse-width modulation (PWM) functionality to any existing 8-channel, digital NI C Series module without requiring programming. These specialty digital functions are configured from the LabVIEW Project, but they run on the FPGA for accuracy and speed. Without compiling, you can perform up to 1 MHz edge counting, pulse-width and frequency measurements, quadrature decoding, and PWM control.
5) Enhanced LabVIEW FPGA Behavioral Simulation – New simulation capabilities improve development time with the ability to test an entire LabVIEW FPGA application without compiling. This includes creating user-defined input data and a fully functional host interface simulation. For example, you now can simulate your FPGA VI with a sine wave on an analog input channel. While this VI runs in simulation, it communicates with your host VI using the FPGA Interface VIs and advanced features such as DMA FIFO.
6) New LabVIEW FPGA IP – The built-in analysis and control functions, FIFOs, and memory items for the LabVIEW FPGA Module have been updated to support the fixed-point data type, so you can perform analysis and signal processing on scaled, calibrated data directly on the FPGA. Additionally, the fixed-point data type now features automatic overflow handling.
The numeric palette now includes divide, reciprocal, and square-root functions with fixed-point support. Among the new processing functions is a fast Fourier transform (FFT) block (and windowing) for spectral analysis, rational resample, and the new LabVIEW Adaptive Filter Toolkit. This LabVIEW FPGA release also introduces the Component-Level Intellectual Property (CLIP) Node, so you have another way to incorporate HDL from any source into your application. As opposed to the current HDL Node, code in the CLIP Node runs in parallel to your FPGA VI, and you can communicate to it with user-defined I/O nodes.
7) Deterministic Expansion I/O – With the new NI 9144 C Series chassis, you can expand CompactRIO systems over a deterministic Ethernet link. CompactRIO systems with dual Ethernet, such as the NI cRIO-9074 controller, can use the dedicated bandwidth of the second port to create a deterministic, distributed system on the NI 9144 chassis. Each 8-slot chassis connects directly using standard CAT 5 Ethernet cabling and contains in/out ports for daisy-chaining chassis without the need for hubs. In the LabVIEW Project, you interact with remote chassis and local chassis in the same way. All chassis are synchronized with the scan engine for low jitter control, and all I/O is programmed using I/O variables.
8) Deployment of LabVIEW Real-Time VIs as Web Services – LabVIEW 8.6 introduces the ability to deploy VIs as Web services on LabVIEW Real-Time targets. By building a VI into a Web service, you can control and monitor LabVIEW Real-Time applications from any Web-capable device without LabVIEW or the LabVIEW run-time engine. The Web server uses firewall-friendly HTTP protocols, so you can use client-side technologies such as HTML, JavaScript, and Flash to develop user interfaces and interpret standard data formats such as XML.
9) Industrial Function Blocks – With LabVIEW Real-Time, you can use 18 new function blocks common in industrial measurement and control applications. These functions, such as PID, timer on delay, counter, one shot, and totalize, are based on the IEC 61131-3 standard. You can configure a function block similarly to an Express VI, but the function block is deterministic and designed for real-time execution.
Function blocks also automatically publish their parameters to the network via shared variables for human machine interface (HMI) communication and status monitoring. Each function block instance has a unique memory space and name and is visible in the LabVIEW Project with access to all parameter variables.
Figure 3. The new NI Distributed System Manager helps you get up and running quickly by adding test panels to CompactRIO.
10) Advanced Debugging – The NI Distributed System Manager offers visibility into memory usage and processor load for CompactRIO controllers using the scan mode. Additionally, the NI Real-Time Execution Trace Toolkit includes updates with new flags for the scan engine, thereby providing low-level insight into the OS.
The scan mode introduces I/O forcing, which is a debugging tool that overrides the value of an I/O variable without stopping or changing your real-time application. You can force inputs to test the response of your application without a physical stimulus and force outputs to override program output values.
A Powerful Combination for Advanced Control
From out-of-box setup to final deployment, the LabVIEW Real-Time Module increases productivity. When combined with the scan mode and LabVIEW FPGA, these tools offer a powerful combination for developing advanced measurement and control applications.
Todd Walter is a senior measurement and control product manager at National Instruments. He holds a bachelor’s degree in mechanical engineering from Virginia Polytechnic Institute and State University.
Kurt Williams is a LabVIEW Real-Time product manager. He holds a bachelor’s degree in electrical engineering from The University of Texas at Austin.
View a demonstration of CompactRIO Scan Mode features.
This article first appeared in the Q3 2008 issue of Instrumentation Newsletter and was later updated for the October 7, 2008, issue of NI News.
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