Supplementary information   
18.16 CPU 410 cycle and reaction times 
  CPU 410 Process Automation/CPU 410 SMART 
358  System Manual, 05/2017, A5E31622160-AC 
Sequence of cyclic program processing 
The table below shows the various phases in cyclic program execution. 
Table 18- 9  Cyclic program processing 
The operating system initiates the scan cycle monitoring time. 
2  The CPU copies the values from the process output images to the output modules. 
3  The CPU reads the status of inputs of the input modules, and then updates the process 
4  The CPU processes the user program in time slices and executes the instructions spec-
5  At the end of a cycle, the operating system executes pending tasks, e.g., loading and 
6  Finally, on expiration of any given minimum cycle time, the CPU returns to the start of 
the cycle and restarts cycle monitoring. 
Elements of the cycle time  
 
Figure 18-27  Elements and composition of the cycle time