Differences Between A Simulated And A Real Cpu - Siemens Simatic S7-1500 Function Manual

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2.6 Differences between a simulated and a real CPU

2.6 Differences between a simulated and a real CPU
The virtual controller cannot fully simulate a real CPU down to the individual details. Even if a
program is downloaded without errors to the CPU and running successfully, this does not
necessarily mean that the virtual controller in the simulation behaves exactly like a real CPU.
Deterministic
PLCSIM Advanced runs on a PC with the Windows operating system. Therefore, the scan
cycle time and the exact time of actions in PLCSIM Advanced are not the same as when
these actions run on physical hardware. This is because that several programs share the
processing resources on your PC.
To provide the best possible deterministic behavior under these conditions,
PLCSIM Advanced as of V2.0 requires one free Core (CPU core) per instance.
If your program depends heavily on the time required to execute actions, then make sure
that you do not evaluate your program based only on the results of the simulation time.
Know-how protection
Projects with know-how protection for blocks can only be simulated if they are enabled for
simulation. You need the block password for this purpose.
Instructions
Instructions are simulated with a few exceptions, see Restrictions for instructions
(Page 351).
Programs that are based on the instructions behave different than real CPUs in the
simulation.
Display of the quantity structure
In STEP 7 the maximum quantity structure that is based on the CPU 1518-4 PN/DP is shown
in the project navigation under "Program info" for all the CPUs.
The maximum quantity structure of the currently simulated CPU is displayed under "Online &
diagnositics".
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S7-PLCSIM Advanced
Function Manual, 12/2017, A5E37039512-AB