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Enhanced Write Filter

The Enhanced Write Filter (EWF"Enhanced Write Filter" protects a volume from write access) is a Microsoft® Windows® XP embedded operating system feature which provides write-protection to a partition on the compact flash (CF) card. All write requests to the partition are redirected to RAM when EWF is enabled. The EWF feature protects the CF image from changes due to sudden power loss, improper shutdown, or other user configurations.When the EWF is active its icon is shown in the system tray, as seen to the right. When the EWF is disabled its system tray icon is a red slashed-circle .

The EWF should be activated on the PAC"Programmable Automation Controller" PAC is a compact controller that combines the features and capabilities of a PC-based control system with that of a typical programmable logic controller (PLC). A PAC thus provides not only the reliability of a PLC, but also the task flexibility and computing power of a PC. Additionally, because they function and communicate over popular network interface protocols, PACs are able to transfer data from the machines they control to other machines and components in a networked control system after the system is running and the PAC configuration is complete. If you want to change the CF image (such as a new KAS version or downloading a new application), then turn off the EWF filter, make the change, and then reactivate EWF.

There are two ways to manage the EWF:

With the EwfWinDllcaller.exe application, located in C:\WINDOWS\system32. This is the preferred method. See Enhanced Write Filter Operational Procedures Using the Application for more information.
From the command line interface. The command line offers more functions than the application but is recommended only for advanced users. See Enhanced Write Filter Operational Procedures using the command line for more information.

Practical Applications

For the KAS RuntimeIn computer science, runtime (or run-time) describes the operation of a computer program, the duration of its execution, from beginning to termination (compare compile time). Within KAS, runtime also refers to the virtual machine that manage the program written in a computer language while it is running installation, using the "commitanddisable" method (via either command line or the application) is strongly recommended. If some operations have been performed previously, the remaining memory will not be sufficient using another method.
For a New PLC"Programmable Logic Controller" A Programmable Logic Controller, PLC, or Programmable Controller is a digital computer used for automation of industrial processes, such as control of machinery on factory assembly lines. Used to synchronize the flow of inputs from (physical) sensors and events with the flow of outputs to actuators and events application download, the "Perform Small Changes on a Protected Volume" method is convenient because the usual PLC application does not exceed 10 MB.

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