Calculating Cycle And Response Times - Siemens SIMATIC CPU 410 System Manual

Table 18- 17 Direct access of the CPUs to I/O modules in the expansion unit with remote link, setting 100 m
Access type
Read byte
Read word
Read double word
Write byte
Write word
Write double word
Note
You can also achieve fast response times by using hardware interrupts; see Chapter
Interrupt response time (Page 373).
18.16.5

Calculating cycle and response times

Cycle time
1. Determine the user program runtime with the help of the instruction list.
2. Calculate and add the process image transfer time. You will find guide values for this in
the tables starting at 16-3.
3. Add the processing time at the scan cycle checkpoint. You will find guide values for this in
Table 16-8.
4. Multiply the calculated value by the factor in Table 16-7.
The final result is the cycle time.
Extension of the cycle time due to communication and interrupts
1. Multiply the result by the following factor:
2. Using the instruction list, calculate the runtime of the program elements processing the
interrupts. To do so, add the relevant value from Table 16-9.
Multiply this value by the factor from step 4.
Add this value to the theoretical cycle time as often as the interrupt is triggered or is
expected to be triggered during the cycle time.
CPU 410 Process Automation/CPU 410 SMART
System Manual, 05/2017, A5E31622160-AC
100 / (100 – "configured communication load in %")
CPU 410-5H
stand-alone mode
11.3 µs
22.8 µs
44.1 µs
10.8 µs
21.9 µs
44.0 µs
Supplementary information
18.16 CPU 410 cycle and reaction times
CPU 410-5H
redundant
16.6 µs
28.1 µs
49.8 µs
16.2 µs
27.3 µs
49.4 ms
369