xPC Target Tutorial

Control System Design Feb. 15, 2004
For more detailed information, see the xPC target manual at: www.mathworks.com

Control Hardware

Connect to your experiment through the network.
IP: 128.113.70.196 xPC target xPC target
IP: 128.113.70.114 xPC target

Student laptops

IP: 128.113.70.116
Software Architecture for Laptop

(host computer)

1. Generate real time code and download to computer

Visual C++

Simulink
xPC Target Real Time Workshop

EXECUTABLE

2. Execute code and interact with real time process

MATLAB GUI xpcrctool.m

MATLAB command line or script

Setting up xPC Target

This GUI configures your computer to communicate with the xPC target computer. 1. At the MATLAB prompt type: xpcsetup <enter> 2. Enter appropriate data 3. Click on Update 4. Click on Close See zoom on next page.

xPCsetup Zoom

Change all settings to match the values shown below, except for the CompilerPath and TcpIpTargetAddress. The compiler path should contain the path to visual C++ on your computer. Use the TcpIpTargetAddress assigned to the box controlling your hardware.
Path to VC++ on your computer
IP address of target computer

Test your xPC setup

Test your setup with a MATLAB xPC target test suite. At the MATLAB prompt, enter: xpctest(noreboot) <enter> It is important to include the noreboot option or the computer will lock up. All is good if there are no errors reported.

Create Simulink Model

( 2 PD controllers )

Data logging

Encoders

D/A converters

Differentiation

Find Simulink block:

Encoder Details
xPC Target\Incremental Encoder\Measurement Computing\PCI-QUAD04
Channel number: There are four encoder channels available.
Count four times per complete cycle of the quadrature signal.
position in radians = 2*pi*Count / (1024*4)
Find Simulink block: xPC Target\D/A\Measurement Computing\PCIM-DAS1602 16

D/A Details

Channel number: There are 2 D/A channels available. Channels 1 and 2 are connected to motor amplifiers. Set the range for both channels: 10 to +10 volts
Reset to initial value after termination Initial value of D/A
Desired voltage signals feed in here

PD Controller Details

Derivative term in the feedback to avoid reference differentiation
Proportional Gain Derivative Gain
Desired Position Controller Output Actual Position
Differentiation ( velocity estimate )
Configure for Compile (1-runtime)
On your Simulink window select: SimulationConfiguration ParametersSolver
Choose fixed step Program will halt after this time
Your real time interrupt rate
Configure for Compile (2-compile)
On your Simulink window select: SimulationConfiguration ParametersReal-Time Workshop
Click on Browse. Select xPC Target from the pop up menu. Screen should now look like this.
Configure for Compile (3-data log)
On your Simulink window select: SimulationConfiguration ParametersReal-Time WorkshopxPC Target options
Enter size of data Logging buffer.

Compile and Download

Using either method 1 or method 2 will cause MATLAB to compile your Simulink Model and download the real time code to the target PC. Method 1 select: ToolsReal-Time WorkshopBuild Model
Method 2 Click on the Build button.

Execute via GUI

At the MATLAB prompt, type: xpcrctool <enter> Click play button to start real time code execution.
Monitor signals during run time. Not Real Time!
Log data to plot after execution.

Monitor Signals via GUI

1. Select Host scope 2. Click Add Scope 3. Select Host 4. Select from pull down menu: ToolsHost Scope Manager 5. Click Add Signals Your Simulink diagram will pop up. You can select any signal to monitor by right clicking on the signal trace.

Data Logging via GUI

After the program has finished, check the outputs box. Click on Plot Logged Data.

The outputs correspond to the outport blocks in your Simulink Diagram

Execute via Command Line

>> start(tg): start execution of real time code >> stop(tg): stop execution of real time code
If you already have a compiled application, you can load it with: load(XPCOBJ, APPNAME)
Data Logging via Command Line
Regardless of how you execute the real time code, the logged data will be available from the MATLAB command line after the code has finished. tg.outputlog(:,1)
The variable tg.timelog is a time vector tg.outputlog is a matrix of logged data
tg.outputlog(:,2) tg.outputlog(:,3)
At the MATLAB prompt: >> time = tg.timelog; >> outputlog = tg.outputlog; >> response =outputlog(:,3); >> plot(time,response);
Parameter Tuning via Command Line
Each parameter will have a parameter name (e.g. P1 P14, etc.) To see the list of parameters and associated Simulink variables: set(tg,'ShowParameters','on') ; <enter> tg <enter>
Parameters P0 P1 P2 P3 P4 P5 P6 P7 = PROP. VALUE -1.000000 1024.000000 3.000000 1.000000 3.000000 1.000000 0.001000 3.000000 PARAMETER NAME Scalar P1 Scalar P2 Scalar P3 Scalar P4 Scalar P5 Scalar P6 Scalar P7 Scalar P8 BLOCK NAME PCI-QUAD04 PCI-QUAD04 PCI-QUAD04 PCI-QUAD04 PCI-QUAD04 PCI-QUAD04 PCI-QUAD04 PCI-QUAD04
To change the value of a parameter: setparam(tg, parameter number, new value); e.g. If we want P3 = 10 we write setparam(tg, 3, 10); <enter>
Execute and Parameter Tuning via Simulink
1. External Mode 2. Connect to Target
3. Run Executable 4. Click on blocks to change parameter values during real time.

xPC Target 2.6

Perform real-time rapid prototyping and hardware-in-the-loop simulation using PC hardware
xPC Target provides a high-performance, host-target prototyping environment that enables you to connect your Simulink and Stateflow models to physical systems and execute them in real time on PCcompatible hardware. xPC Target includes proven capabilities for rapid prototyping and hardware-in-the-loop simulation of control and audio/speech signal processing systems. xPC Target enables you to add I/O interface blocks to your models, automatically generate code with Real-Time Workshop and Stateflow Coder, and download the code to a second PC running the xPC Target real-time kernel. You can use any PC with Intel 386/486, Pentium, or AMD K5/K6/Athlon processor as your real-time target. The target PC can be a desktop computer, an industrial computer such as xPC TargetBox PC/104, PC/104+, , CompactPCI, all-in-one embedded PC, or any other PC-compatible form factor. With the xPC Target Embedded Option (available separately), you can deploy your real-time embedded systems on PC hardware for production, data acquisition, calibration, and testing applications.

KEY FEATURES

Runs applications generated from Simulink and Stateflow models using a real-time kernel on any PC Supports any desktop PC, PC/104, CompactPCI, industrial PC, or single-board PC computer as a real-time target system Achieves sample rates approaching 100 KHz, depending on processor performance level and model size Supports more than 250 standard I/O boards, with an extensive I/O device driver library, including driver source code Enables signal acquisition and parameter tuning from the host or target PC Acquires and logs data in real time to RAM or the file system of the target PC Displays data and signal traces on the host PC, target PC, or both Provides an integrated host GUI and an object-oriented, MATLAB command-line interface to access the target application running on one or more target PCs Offers host-target communication via RS-232 or TCP/IP protocol (direct, LAN, or Internet) Supports the programmatic development of custom graphical user interfaces for access to signals and parameters
Prototyping setup using a laptop PC as the host computer and a single-board computer as a real-time target.

Magnetic Levitation

Setpoint 0.5 Manual Switch

Signal Generator

Sum Scope butter

Command Control Feedback

Adapter
RT In RT In Digital IIR Filter Design ManualSwitch

RT Out RT Out

PID Controller
Magnetic levitation model (above), created with Simulink and converted to a real-time application that runs on the target PC with the display (right) showing the real-time signals. The application can run with a sample time as low as 20 microseconds.

Working with xPC Target

With a host computer running MATLAB, Simulink, Real-Time Workshop, xPC Target, and a C compiler as your development environment, you can create real-time applications and run them on a target PC using the xPC Target real-time kernel. The xPC Target real-time kernel provides deterministic performance on PC hardware for running real-time applications. You control execution on the target PC from MATLAB, using either a graphical or a command-line interface, supplied or custom host graphical user interfaces (GUIs), a standard Internet browser, or the target PC command-line interface. You can tune model parameters. You can acquire and view signals immediately or store them for later analysis. You can also view signals and target status information directly from your target PC. Running xPC Target on your target PC has no effect on any software that is already installed on the target PC hard drive. Once you reboot your target PC, you can resume its normal operation as a standard PC running Windows, Linux, or other PC operating system and application software. xPC Target does not access your target PC hard drive unless you explicitly use the file system capability.

High-Performance Real-Time Kernel
Using standard PC hardware and commercial off-the-shelf I/O boards, xPC Target converts a standard PC into a real-time rapid prototyping or hardware-in-the-loop system. High performance is achieved by booting the real-time kernel rather than DOS or Windows. Both interrupt-handling and polling modes are supported within the real-time kernel. Interrupt mode is the default and provides
the highest application flexibility. Polling mode runs with less overhead, enabling you to achieve smaller sample times for applications, although access to the running application is more restricted. The kernel is tuned for minimal overhead and maximum performance. Using a highperformance Intel Pentium or AMD Athlon processor, you can achieve sample rates approaching 100 KHz.
The combination of MATLAB, Simulink, Real-Time Workshop, and xPC Target creates an integrated simulation environment in which you can model, simulate, and analyze complex dynamic systems.
Communicating Between Host and Target Systems
A single communications link connects the host and target computers. You design your application on the host computer and download the real-time application to the target PC. The same communications interface is used to pass commands and parameter changes to the target PC. You can choose either RS-232 or TCP/IP communications. RS-232 communication uses a null modem cable and a standard PC COM port on both the host and target PC. RS-232 communication supports baud rates up to 115 kBaud and provides the advantage of easier setup, without requiring an Ethernet card. TCP/IP communication is faster, providing data rates up to 100 Mbit/sec over any distance. xPC Target includes both an RS-232 cable and a PCI Ethernet card for the target PC. xPC Target Explorer runs on the host and interactively monitors and controls a real-time xPC Target application run.
Controlling the Target Application
The target application control functions let you download target applications onto the target PC, start and stop execution, change stop time and sample time, detect CPU overloads, and query statistics about execution performance and CPU usage.
Accessing the Target Application
The underlying layer of communication with the target PC is an object-oriented, MATLAB command-line interface, which you use to pass commands to the target. You can also include the commands in M-files for detailed batch testing. The command-line interface consists of three function groups: target application control, parameter tuning, and signal acquisition (data acquisition). Graphical user interfaces, built upon the command-line interface, can be used on the host or the target PC, or through a standard Internet browser. The host GUI, xPC Target Explorer, enables you to configure, control, and monitor operations of the target system, including access to multiple targets running concurrently.

(Opening a dialog box for a source block causes Simulink to pause. While Simulink is paused, you can edit the parameter values. You must close the dialog box to have the changes take effect and allow Simulink to continue.)

Tuning Parameters

xPC Target includes functions for tuning model parameters on the target PC. After downloading the target application, you can use the command-line interface to alter parameter values either before execution of the target application or while the target application is running. You can also use Simulink external mode for parameter tuning. In this mode, the Simulink model running on the host computer is used as a GUI. Once you change a parameter in your Simulink model, the new parameter value is downloaded to the target PC.

Acquiring Signals

You can control and access signal acquisition devices via the xPC Target kernel running on the target computer. You can perform signal logging to acquire signals during the entire execution run of an application. In signal acquisition mode, data is stored in real time in RAM or in the file system on the target PC. Once the execution stops, you can upload acquired data to the host computer. With the various logging options, this mode is suitable for step-response acquisitions. An alternative mode of signal acquisition, signal tracing, lets you capture and display bursts of signal data during real-time execution of your model. This behavior is similar to that of a digital oscilloscope.
Defining and Controlling Scopes
Graphical display components called scopes can be defined and controlled easily. You can define which signals and the number of samples to trace. You can also specify trigger modes and upload the acquired data bursts. You can define multiple scopes, each acquiring different signals and each using different triggering modes. Multiple signals can be displayed within each scope.
Monitoring Operation from the Target PC
A simple user interface runs on the target PC and displays information on the status of the target application while it runs. It also displays signal traces. Because of the highly optimized graphics routines used on the target PC, dynamic signal tracing delivers display update rates typical of digital oscilloscopes. You can use a simple command-line interface to execute commands for control, signal acquisition, and parameter tuning directly from the target PC.

Controlling the Target Application Through a Web Browser
The xPC Target kernel includes a compact Web browser interface that enables you to fully control the target application, including tuning parameters, viewing signal histories, and configuring target scopes from any computer. MATLAB and Simulink products do not need to be installed on the host computer. During the build process, you can define an access level that enables you to restrict which target application properties can be changed.
Controlling and Monitoring Operation Controlling Operation from the Host PC
Built on the xPC Target command-line interface and MATLAB, the xPC Target Explorer simplifies system configuration, signal tracing setup, and operation. You can define scopes; add, remove, or exchange signals; and select triggering modes interactively. Host scopes continuously upload the signal traces and display them on the host PC. The xPC Target Explorer also lets you control scopes displayed on the target PC monitor.
xPC Target Explorer defines all the target system build, signal acquisition, compiler, and communications options.

Programming Custom GUIs

xPC Target includes two extensive application interfacing capabilities: the xPC Target API and the COM API. Both interfaces provide full access to the controls, signals, and parameters of xPC Target for use in developing custom GUIs. You can connect your own GUIs, which can be developed with Visual Basic, Visual C/C++, Tcl/Tk, Perl/Tk, and other programming tools, using subroutines or COM objects. You can use these interfaces with any xPC Target application, as long as they are running on a computer that can connect to your target system.
Using a standard Web browser you can connect to and control your target application from any computer.
Interfacing with I/O Devices
An extensive set of I/O device drivers lets you choose PCI, CompactPCI, PC/104, and ISA bus I/O boards from leading hardware vendors to interface with sensors, actuators, and other physical devices. Supported I/O includes analog to digital, digital to analog, frame-based analog input, digital inputs and outputs, CAN bus interfaces, counters, encoders, pulse train generation and capture, professional audio input and output, GPIB, serial ports, synchro-resolvers, and LVDT/RVDT measurement and simulation. For a complete and up-to-date list of supported I/O drivers, visit www.mathworks.com/xpctarget/hardware

Using Audio Devices

Professional audio support for xPC Target enables audio designers to acquire data from an audio source, process the data with prototype algorithms, and output the modified audio to an audio speaker system, all in real time. To provide this capability, xPC Target works with the BittWare Audio-PMC+ audio I/O board, integrating its versatile audio I/O capability with Simulink and Signal Processing Blockset algorithms.

Accessing Shared Memory for Multiprocessing
xPC Target includes Simulink I/O driver blocks that enable communication between target applications running on a number of target PCs. These I/O drivers, using shared memory technology from SBS Technologies, Systran Corporation, or VMIC, enable multiprocessing execution of large-scale, real-time applications in cases where a single target PC cannot handle the computational complexity. With this technology, data is shared between target PCs and other connected shared memory systems in real time with very low read and write latencies. This technology also supports broadcasting interrupts, allowing full synchronization of all connected target PCs.

Working with CAN Devices

The xPC Target I/O device library includes CAN device drivers that support boards from Softing AG. The xPC Target CAN drivers enable you to interface with a CAN fieldbus network to provide communication on a CAN network between real-time applications and remote sensors and actuators. A custom user interface, developed using Visual Basic and xPC Target API COM objects, is used to monitor signals during a real-time xPC Target application run.
xPC Target Embedded Option Deploying Real-Time Applications
The xPC Target Embedded Option is an extension to xPC Target that enables you to deploy and run your system on cost-effective PC hardware. It includes two modes of operation: DOS-loader and stand-alone. The DOS-loader mode enables you to configure the xPC Target kernel to run automatically each time your development target is reset. The kernel is then ready to receive a real-time application from the host computer. The kernel can use any boot device, including floppy disk, hard drive, or flash disk. To create and deploy an embedded application, you can use the xPC Target Embedded Option stand-alone mode to configure a boot device for your target PC(s) that automatically loads and executes your real-time application without a connection to a host computer or operator intervention. The stand-alone mode enables deployment of systems that begin execution at startup. In this configuration, software modules, including your real-time application, can be installed on floppy disks, hard drives, or flash disks. You can use a keyboard and monitor on the target PC, but they are not required. With a keyboard, you can control the target application with the target PC command-line interface. You can also control the target application using custom GUIs or the Web browser interface when deploying the target application with the xPC Target Embedded Option. GUIs developed with the xPC Target API and the COM API are freestanding and deployable, and can be used on any host Windows system without the need for MATLAB.

Configuring Target Hardware Systems
You can use any target PC hardware with xPC Target, including xPC TargetBox for rapid prototyping applications. For information on configuring a variety of target PC systems, including I/O components, refer to the xPC Target Selecting Hardware Guide and the Interactive Hardware Selection Guide at www.mathworks.com/xpctarget/hardware
Platform and System Requirements
Microsoft Visual C/C++ compiler version 5.0 or above or Watcom C/C++ compiler 10.6 or 11.0 DOS license (for xPC Target Embedded Option only) For additional platform and system requirements, visit www.mathworks.com/products/xpctarget

Required Products

MATLAB Simulink Real-Time Workshop

Related Products

Stateflow. Design and simulate eventdriven systems Stateflow Coder. Generate C code from Stateflow charts xPC TargetBox. Industrial PC for real-time rapid prototyping For more information on related products, visit www.mathworks.com/products/xpctarget

Supported Hardware

xPC Target supports more than 250 commercial I/O boards. For a complete list, visit www.mathworks.com/xpctarget/hardware
For demos, application examples, tutorials, user stories, and pricing: Visit www.mathworks.com Contact The MathWorks directly US & Canada 508-647-7000 Benelux France Germany Italy Korea Spain Sweden Switzerland UK +31 (0)+33 (0)14 +49 (0)750 +39 (011) +82 (0)5114 +00 +46 (8)00 +41 (0)+44 (0)200
Visit www.mathworks.com to obtain contact information for authorized MathWorks representatives in countries throughout Asia Pacific, Latin America, the Middle East, Africa, and the rest of Europe.
Tel: 508.647.7000 info@mathworks.com www.mathworks.com

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2004 by The MathWorks, Inc. MATLAB, Simulink, Stateflow, Handle Graphics, and Real-Time Workshop are registered trademarks, and TargetBox is a trademark of The MathWorks, Inc. Other product or brand names are trademarks or registered trademarks of their respective holders.