1.4.4. Windows CE Specific Information

Under Windows CE, we use the timer interrupt for the tick source of the runtime scheduler. All PLC tasks are created as operating system threads and are triggered by events from the runtime scheduler. The scheduling of the tasks is done by the Windows CE scheduler.

Win CE specific settings in the runtime system configuration file (*.cfg):

The communication cycle interval can be configured in order to control CPU load:

[ComponentManager]
WinCE.CommCycleInterval=5

The sleep duration after each comm cycle will be 5ms in this case. The default before version 3.5 Sp4 was 1 ms which generated a relatively high CPU load. Therefore the default value had been changed to 10 ms from 3.5 Sp 4 on.

Under Windows CE it is not possible to handle relative paths. So the default behavior of file transfer and access under Windows CE has changed as from V3.4 SP4. From this version on, by default in the device dialog there is no access to paths beyond the “working directory”.

For activating the old behavior (access to all files, e.g. also in the root directory), the following setting can be added to the runtime system configuration file:

[SysFile]
WinCE.AllowRootAccess=1

An explicit folder can be defined, to which the Target-Visualization files (image files, textlists etc.) get redirected. By default, that is when the setting is missing, they get stored in a subfolder “visu” of the runtime system folder!

[SysFile]
WinCE.VisuFilePath=\\Hard Disk\\SpecialFolder

Because CE cannot handle relative paths, the complete path of the desired visu files folder must be specified in the setting!

Example: Setting „WinCE.VisuFilePath=\Hard Disk\SpecialFolder\SpecialVisuFolder” effects that folder „SpecialVisuFolder” will be created as a subfolder of „\Hard Disk\SpecialFolder” (in case it does not yet exist) and the visualization files get stored there. The path “Hard Disk\SpecialFolder” must already exist!

If SRAM is used for retain handling with a specified address it might be necessary to have the following additional setting.

[SysShm]
WinCE.DisableMapPhysicalInVirtualAllocCopyEx=1

As the Sysdriver uses the VirtualCopy function for mapping hardware addresses to user program the behavior here depends on the CE image. This setting has to be set on some devices where it is necessary to have the “PAGE_PHYSICAL” flag in the call of “VirtualCopy” but not in the call of “VirtualAllocCopyEx”. Otherwise it is possible that the address that the Sysdriver returns to the user program is not correct and retains do not work.

Per default, the CE runtime system tries to change the system memory division to get more program memory and less storage memory. This behavior can be suppressed by the setting

[SysGraphic]
WinCE.DontChangeMemorySettings=1

So other applications will get more program memory.

Up to version 5, Windows CE processes have a 32 MB address space which may be too small for big applications. To overcome this restriction (only if the device has more than 32 MB physical RAM), the OEM can change the memory layout of the device description (example for a 32 MB area)

<ts:setting name="minimal-area-size" type="integer" access="visible">
<ts:value>0x2000000</ts:value> </ts:setting>
<ts:setting name="maximal-area-size" type="integer" access="visible">
<ts:value>0x2000000</ts:value> </ts:setting>

and the runtime configuration file

[SysMem]
WinCE.CE5BigAreaSize=0x2000000

As from V3.5 there is a new source file SysDrv3SCECustom.cpp for customer specific adaptations. A new project file SysDrv3SCECustom.vcproj for CE6 and SysDrv3SCE7Custom.vcproj for CE7 is available to build the dll by including the SysDrv3SCE.obj and the customer specific source file.