Siemens S7-300 appendix Calculating method for calculating the cycle/response time, Cycle time

Cycle and reaction times

5.4Calculating method for calculating the cycle/response time

5.4Calculating method for calculating the cycle/response time

Introduction

This section gives you an overview of how to calculate the cycle/response time.

Cycle time

1.Determine the user program runtime with the help of the Instruction list.

2.Multiply the calculated value by the CPU-specific factor from the table Extension of user program processing time.

3.Calculate and add the process image transfer time. Corresponding guide values are found in table Data for calculating process image transfer time.

4.Add the processing time at the scan cycle checkpoint. Corresponding guide values are found in the table Operating system processing time at the scan cycle checkpoint.

5.Include the extensions as a result of testing and commissioning functions as well as cyclical PROFINET interconnections in your calculation. These values are found in the table Cycle time extension due to testing and commissioning functions. The final result is the cycle time.

Extension of the cycle time as a result of interrupts and communication load

100 / (100 – configured communication load in %)

1.Multiply the cycle time by the factor as in the formula above.

2.Calculate the runtime of interrupt processing program sections with the help of the instruction list. Add the corresponding value from the table below.

3.Multiply both values by the CPU-specific extension factor of the user program processing time.

4.Add the value of the interrupt-processing program sequences to the theoretical cycle time, multiplied by the number of triggering (or expected) interrupt events within the cycle time. The result is an approximation of the physical cycle time. Note down the result.

See also

Cycle extension through component-based automation (CBA) (Page 5-11)

CPU 31xC and CPU 31x, Technical data	5-19
Manual, Edition 08/2004, A5E00105475-05