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ADwin
Process Management
a higher level at any time. The processor T11 keeps strictly to the priority levels for process management (see chapter 6.2.3 on page 117).
Low-priority processes of the same priority level participate in time slicing.
Here the operating system apportions the computing time to the process
cycles alternating and in equal time slices. One time slice takes 2ms (processor T9) or 1ms (processors T10, T11) on average.
Low-priority processes must always be time-controlled. The cycle time (processdelay) can be set in discrete intervals; interval size see fig. 17 on
page 115.
Processes with low-priority on principle do not influence the time characteristic
of high-priority processes, but vice versa they surely do.
6.1.4
Communication Process
The communication process has a priority level between the priorities "high"
and "low". Therefore it can interrupt low-priority process cycles any time and
can be interrupted by high-priority process cycles.
If the computer requests information from the ADwin system, the communication process must respond within 250ms or a time-out will occur, the communication between the computer and the ADwin system may be interrupted. In
this case the message The ADwin system does not respond will be displayed and the system will have to be reinitialized by rebooting the ADwin
system. The time-out is independent of the communications interface, either
USB or Ethernet.
The cause of an interruption in the communication is that the communication
process does not have enough processor time allocated to it. This can be
caused by the following facts:
–
the processdelay of the high-priority processes is too short or
–
the processing time of a high-priority process cycle is too long.
More about this subject can be found in chapter 6.3.2 on page 121.
6.1.5
Memory fragmentation
The operating system of the ADwin system cares for storing processes, arrays
and variables at an adequate memory position and using them correctly.
Therefore the user normally has no problems with memory management
which thus would need no explanation.
Under certain circumstances, the error message „Not enough memory or
memory access error. Please reboot the ADwin system.“1 occurs.
Often, the reason is an external memory fragmentation, which arises from pro-
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