Most PC based vision systems use the Microsoft Windows operating system. The wide range of development tools, many developers and an interface that is familiar to a large user base, indicates that it is an easy platform to use. One of the drawbacks of the platform, however, is also this familiarity, so users of a machine vision system on Windows can install additional software and make changes to settings. Standard Windows is also vulnerable to corruption if its not shut down correctly, meaning uninterruptable power supplies should be used if there is a risk of regular power loss.
Windows has traditionally been a desktop and server operating system requiring significant PC resources. With Windows 7 we have seen a reduction in the minimum hardware requirements and the embedded version of the operating system has become easier to configure, to create small footprint devices. With Windows 10 a new version called IOT (Internet of things) will deliver the smallest foot print for very embedded applications.
Windows Embedded is a special version of the operating system that allows OEMs to create custom builds by removing unwanted parts and adding special features not possible in the standard version. While the version has been available for many years it was extremely difficult to use, as many parts of the software had reliances on other modules. Since Windows 7 the tools to manage these conflicts have been improved such, that the time to create a custom build has been reduced to a level that makes it more viable for lower quantity applications such as vision systems.
All PCs from STEMMER IMAGING are now available with Windows Embedded with a set of utilities to configure the system to overcome the limitations of the standard version of the operating system. Our standard Windows Embedded disk image is based on the full version of Windows with the following additional features.
■ Disk write filters
This allows parts of the disk to be locked to read-only such that any settings that are changed during use are lost at reboot. A common setting is the operating system and install files are locked and only the application settings, log files and image storage areas being open for write access. This solved two issues: firstly on power loss the system is not at risk of disk corruption and secondly general users cannot tamper with the system.
■ Keyboard filter
Windows has a number of keystrokes such as Ctrl/Alt/Del to access utilities and launch applications. By filtering out these commands a user is unable to access these and hence the computer need not appear as Windows.
■ Logo on boot
This option removed the Windows logo on boot up and can be replaced with a custom logo.
■ Hiding the Windows menu
With Windows Embedded the shell programme that launches the menu system can be replaced so the Windows start menu is disabled and replaced with, for example, the vision application. With the above configured the Windows PC no longer looks or behaves like a standard PC and becomes a dedicated vision system and is protected against tampering and unexpected power loss. STEMMER IMAGING's Windows Embedded integration service can implement this for you to your specifications.
■ Advanced configuration
As standard we install all operating system components as this ensures compatibility with the majority of Windows applications. With Windows Embedded it is possible to remove elements of the operating system to further improve performance and reduce the memory, disk and processor resources needed to run. Our integration team can build an image to meet your requirements on request.
■ STEMMER IMAGING EMBEDDED UTILITY
To simplify the configuration and maintenance of the above features STEMMER IMAGING have developed a utility to provide the maximum protection and flexibility using Windows Embedded. The Windows shell which is launched on start up is replaced by a utility that runs in the background. This utility can launch a number of programmes on start up such as the vision system application. To configure this utility a key sequence can be entered or a command can be called from the vision system application. Users are presented with a PIN code to protect access. On entering the code a menu as shown below is launched which allows the above features to be enabled and disabled hence switching the PC from behaving like a standard PC and the locked down custom version. This utility can be installed and configured on our Windows Embedded PC's on request.
Linux, like a number of operating systems such as Mac OS is based on UNIX. Initially an open source version is developed and supported by the community. To create stability and provide support to a wider user base a number of commercial distributions have become available such as Debian, Ubuntu and Android the popular smart phone operating system.
When using open source versions the key advantage is the open source nature and no license costs. The disadvantages include fewer developers familiar with Linux and the open source nature implies that care has to be taken to ensure correct version control. Our experience in Linux is that it is generally adopted in machine vision applications where the device is not a PC such as an ARM based smart camera, or where the quantities are high and price pressure is significant.