44
The PC's part of the calculating capacity can be set with a slider.
Depending on the size of the PLC application and the defined cycle time the slider has to be adjusted to
the PLC load. The slider can be set between 10% and 85%. The current load (bar) indicates whether the
allowed maximum for executing the PLC cycle is sufficient.
If the bar is near 100%, there is a danger of cycle overflows! In this case set the slider higher (towards
85%). If this is not possible because of the applications in Windows (e.g. bad screen opening times of
zenon) the cycle time of the straton application has to be increased.
Attention
If the bar reaches the 100% mark, there is a danger of cycle overflows!
45
Examplee
Slider at 10%, cycle time 10ms:
The straton RTK must process the PLC program in 1 ms which equals 10% of the set
cycle time of 10 ms.
Slider at 50%, cycle time 5ms:
For executing the PLC program 2.5ms are available for the straton RTK.
Slider at 85%, cycle time 20ms:
For executing the PLC program 17ms are available for the straton RTK.
The following formula can be used to find out, if the setting of the slider does not
lead to cycle overflows in combination with the cycle time:
cycle time > (100 / Sliderposition [%] ) * calculating time
In order to find out the calculating time of the PLC cycle, click Shift+Alt+A and note
the value Max. Cal. Time [µs].
Assumption:
Max. cal. time:
274µs
Slider position
: 50%
Set cycle time:
1ms (1000µs)
Calculation:
(100/50)*274 = 548µs
This means that the defined cycle time of 1 ms is sufficient.
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Attention
Please keep in mind: If you do not stick to the described formula, the determinism which is
based in the cycle time is not given anymore!
Current [µs]
Current system latency (
see also Runtime cycle
(on page 38))
Maximum [µs]
Maximum system latency (since the start of the Runtime)
Cal. time [µs]
Current calculation time of the last cycle
Max. cal. time [µs]
Maximal calculation time for a PLC cycle (since the the start of the
Runtime)
Cycle time [µs]
Current cycle time
Min. cycle time [µs]
Minimal cycle time (since the start of the Runtime)
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Max. cycle time [µs]
Maximal cycle time (since the start of the Runtime)
Cycle overflow [1]
Counter for cycle time exceedance (since the start of the Runtime)
Driver overflow [1]
Counter for failed PLC cycles of Windows (non-realtime) drivers (since
the start of the Runtime)
The value of the cycle time can always only be a multiple of the HAL Timer Periode (time basis). The
time basis depends on the selected timer and its time basis (see also
straton RTK configuration
(on page
49)). That means: A set cycle time of 10 ms of a hardware with a time basis of 122 µs is not executed
with exactly 10,000 ms but with 10,004 ms.
5.7.1
Restrictions and requirements of the straton RTK
The hardware (PC or IPC) and the operating system (Windows® XP, XPe or Vista) must support ACPI:
ACPI-Multiprocessor-P
ACPI-PC (Advanced Configuration and Power Interface)
ACPI-Uniprocessor-PC
You can check whether your PC supports ACPI in the system control (system/device
manager/computer).
The straton RTK is supported from the following processor generations on:
Pentium II or younger
AMD Athlon XP or younger
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The straton Real Time Kernel (RTK) runs as a separate process on the hardware level independent of the
operating system. The straton Runtime runs on Windows
®
. The real-time-enabled straton RTK has a few
restrictions compared to the straton Runtime.
The following funciton blocks are not processed directly in the Kernel Mode, but only emulated:
all file operations (category 'Files')
all TCP/IP modules (category 'TCP-IP')
Following function blocks are not supported by the straton RTK:
day_time_local (Category 'Clock')
Info
In order to determine exactly which function blocks the straton standard library supports,
use the feature of the configuration of the straton Workbench (main menu:
Project/Configuration/Upload
).
After you have selected the configuration, the function blocks which are not supported are
marked red in the library.
The following straton I/O drivers are executed by the straton RTK in Kernel Mode (real time):
Profibus (Hilscher CIF Profibus)
Hilscher SYCON universal (Hilscher SYCON configuration)
You can find more information about supported I/O drivers here:
straton I/O driver support
(on page
68)
There is a small chance that the real time driver of the straton RTK must be registered and de-registered
manually. In order to do this start the command prompt via:
Start > execute > cmd
.
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