Use a Single Software Tool for HMI and Logic Programming
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Developing control applications requires expertise in several areas, including process logic, control system design, and user interface design. When using programmable logic controllers (PLCs) and traditional software tools, engineers need to be proficient with both logic programming tools and human-machine interface (HMI) software development packages. These disparate tools add development time and training costs for developing control applications.
LabVIEW – The Alternative to Disparate Software Applications
National Instruments LabVIEW software provides an alternative with a single development environment for logic and HMI development. NI LabVIEW programmers have been using the unique combination of an interactive front panel user interface and graphical dataflow programming environment to develop integrated user interface and control programs for 20 years. New features in LabVIEW 8, such as the LabVIEW Project and shared variables, make creating user interfaces for HMI applications even easier. For deploying these user interfaces, NI has released three new hardware targets.
Figure 1. Deploy NI LabVIEW to new NI HMIs and industrial touch panels.
These new HMIs and industrial touch panels combined with LabVIEW 8 offer a single software environment for developing logic, operator interface, and supervisory control and data acquisition systems. Figure 1 shows the three new HMIs based on functionality and typical hardware platforms:
1. Operator interfaces for Windows-based systems
2. Front panels for LabVIEW Real-Time controllers
3. Industrial PCs with integrated touch screens
To deploy operator interfaces from Windows-based systems such as PXI, simply add a touch screen display for interactive user interfaces. For embedded real-time targets, Windows CE devices provide rugged displays programmed with the LabVIEW PDA Module using TCP/IP commands. A PC with an integrated touch screen delivers PC-based I/O for data acquisition systems or offers a display that you can connect to other programmable automation controllers (PACs) to create distributed I/O systems. The LabVIEW Datalogging and Supervisory Control (DSC) Module adds supervisory and SCADA functionality to these HMI applications.
1. Operator Interfaces for Windows-Based Systems
You can easily deploy LabVIEW user interfaces for Windows-based systems by adding a flat panel touch screen. For example, the new 15 in. NI FPT-1015 flat panel touch screen provides a display through a standard VGA port and an interactive touch screen through USB. The FPT-1015 offers an industrial touch screen for any PC, CompactPCI/PXI, or industrial PC with a VGA and USB port running Windows XP/2000. A typical application for deploying the FPT-1015 is an operator interface for PXI factory floor test systems.
After developing a test system, engineers often deploy the LabVIEW executable and an NI TestStand sequence as the final system on the factory floor. Operators need intuitive operator interfaces that display pass/fail results and test information. With LabVIEW, you can develop these operator interfaces in parallel with the test program. Deploying these operator interfaces is as easy as adding interactive touch screens such as the FPT-1015.
2. Front Panels for LabVIEW Real-Time Controllers
LabVIEW Real-Time controllers offer reliability and determinism programmed through Windows PCs. To deploy the LabVIEW front panels you create in parallel with embedded logic, you have options for either Windows or industrial Windows CE .NET displays:
• Remote Web Panels for Windows Browsers – The LabVIEW Web Publishing Tool automatically generates HTML code and then publishes a user-created LabVIEW front panel as an interactive Web page with the LabVIEW Web server. Multiple PCs can access these LabVIEW front panels, and you can grant one controller control access. You can set security and access rights to limit access by IP address so remote operators or managers can securely monitor or update values.
• Windows CE .NET Industrial Touch Panels – To create interactive front panels without using a Windows Host, the LabVIEW PDA Module compiles LabVIEW applications for Windows CE .NET industrial touch panels such as the new NI TPC-2006 touch panel computer. Standard networking protocols such as TCP/IP, IrDA, Bluetooth, and 802.11 provide communication between PDA applications and LabVIEW Real-Time controllers.
LabVIEW offers several tools for deploying HMI displays including the TCP/IP communication palette and example programs. The LabVIEW PDA Module includes the LabVIEW PDA Project Wizard, example VIs, and LabVIEW PDA templates for creating user interfaces on industrial touch panels. National Instruments has developed several white papers on architecting TCP/IP communication from real-time PACs, including:
• “Creating LabVIEW PDA Applications to Communicate between PACs and Industrial Touch Panels”
• “Simple TCP/IP Messaging Protocol”
• “Command-Based Architecture for LabVIEW Real-Time”
These white papers include a LabVIEW PDA Module overview and a detailed analysis of how to architect TCP/IP communication using a simple TCP/IP messaging protocol and a more advanced command-based architecture built on the simple TCP/IP messaging protocol. This architecture creates parallel loops that execute with different priorities for separate communication and real-time tasks to reduce jitter. A library of example VIs for sending messages between host and target applications using TCP/IP messaging is also available as a FREE download.
3. Industrial PCs with Integrated Touch Screens
LabVIEW runs on industrial PCs with integrated touch screens such as the new NI PPC-2015 panel PC. The PPC-2015 is an integrated HMI and industrial PC that runs Windows XP on a Pentium 2.0 GHz processor. The combination of LabVIEW and the PPC-2015 is ideal for the following two typical application types:
• Distributed I/O Systems with NI PACs – Add distributed I/O or remote PAC targets to the panel PC using Ethernet and the new features available in LabVIEW 8. Creating distributed systems is now easier with the LabVIEW Project because the project provides access to distributed hardware targets from a single LabVIEW program. LabVIEW shared variables offer easy access to the I/O on distributed PACs. The PPC-2015 can host shared variables from multiple real-time targets including Compact FieldPoint, CompactRIO, and PXI real-time. Then, using LabVIEW, create HMI displays for these real-time targets by dragging the shared variable from the LabVIEW Project to a front panel hosted on the panel PC, and an appropriate front panel control or indicator is automatically created.
• Integrated PC-Based DAQ Systems – For integrated PC-based data acquisition systems, the NI panel PC provides connectivity with five USB ports and two half-length PCI slots. Create integrated systems with new USB-based data acquisition (DAQ) and select from a wide range of NI M Series DAQ hardware and industrial digital I/O hardware with software support through LabVIEW and NI-DAQmx. Also add motion or vision through either PCI motion and vision cards or Ethernet-based PACs.
Alarm and Event Functionality with LabVIEW DSC
Add configuration-based alarms and events, real-time and historical trending, and a database for distributed logging to these panel PC applications with the LabVIEW DSC Module. In addition, the new LabVIEW 8 DSC Module provides:
• Programmatic shared variable creation
• Support for shared variable import/export of comma-separated values (CSV) files
• Event structure integration for value-change notification of alarm and event changes
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Table 1. New NI HMIs and industrial touch panels offer device OS, display size, connectivity target, and connection and driver/communication method options.
One Tool for HMI and Logic Application Development
The new HMIs and industrial touch panels provide hardware targets for deploying HMI applications based on the new features in LabVIEW 8 distributed intelligence. Reduce development time by using a single development tool to program multiple targets and develop HMI and logic applications.
Robert Jackson
Compact FieldPoint and HMIs
Marketing Engineer
robert.jackson@ni.com
Download data sheets for the new industrial touch panels or the white papers and example code discussed in this article, or to participate in an online Web event.
This article appeared in the Q1 2006 issue of Instrumentation Newsletter.
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