| xPC Target | |
Software Architecture
xPC Target Embedded Option creates additional files that you add to your target PC DOS boot device. With the DOSLoader mode, an autoexec.bat file is generated. This file enables DOS to automatically execute the file xpcboot.com once the target PC is booted. The file autoexec.bat includes an argument that invokes a *.rtb file containing the xPC Target kernel. Therefore, when the boot device invokes DOS, the autoexec.bat file then starts the xPC Target kernel. All these files are placed on a floppy disk when you click BootDisk from the xpcsetup GUI. Your real-time application is not copied to the boot device. You create the real-time application later by clicking Build.
The StandAlone mode operates in a similar fashion, with a few important differences. From the xpcsetup GUI, after choosing StandAlone, you only click Update to make your current selections active. When you later click Build, an autoexec.bat file and the xpcboot.com file are placed in a subdirectory that is created within your current working directory. This directory is named modelname_xpc_emb. In addition, the build process creates your target application and combines it with the xPC Target kernel. This combined *.rtb file is also placed in the same modename_xpc_emb subdirectory. You copy these files onto any DOS boot device. Then, upon booting DOS, the file xpcboot.com is invoked with the kernel and with your target application. If you choose to use target scopes with your stand-alone application, you can do so provided appropriate xPC Target Scope blocks are added and configured prior to code generation.
A small DOS executable called xpcboot.com is the core module of the Embedded Option. This module is used in both the DOSLoader mode and the StandAlone mode. The module xpcboot.com is executed from DOS. It loads and executes any xPC Target application. The first argument given to xpcboot.com is the name of the image file (*.rtb) to be executed. This image file contains the xPC Target kernel and options, such as whether you are communicating using a serial cable or TCP/IP, and the ethernet address you have assigned to the target PC.
Before starting the kernel, you must first boot the target PC under DOS. The module xpcboot.com is then automatically executed under DOS by autoexec.bat. To boot the target PC under DOS, you must first install DOS on the target PC boot device. The xPC Target Embedded Option does not have specific requirements as to the type of device you use to boot DOS. It is possible to boot from a floppy disk drive, hard disk drive, flash disk, or other device where you have installed DOS.
DOS is only needed to execute xpcboot.com and read the image file from the file system. After switching to the loaded kernel, and then executing the xPC Target application, DOS is discarded and is unavailable, unless you reboot the target PC without automatically invoking the xPC Target kernel. Once the xPC Target application begins execution, the target application is executed entirely in the protected mode using the 32-bit flat memory model.
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