Supplementary information
18.16 CPU 410 cycle and reaction times
CPU 410 Process Automation/CPU 410 SMART
370 System Manual, 05/2017, A5E31622160-AC
The result is an approximated
. Note down the result.
Table 18- 18 Example of calculating the response time
3. Next, calculate the delays in the inputs and
outputs and, if applicable, the cycle times on the
3. Multiply the actual cycle time by factor 2.
4. Next, calculate the delays in the inputs and
outputs and the DP cycle times on the
PROFIBUS DP network.
4. The result you obtain is the
5. The result you obtain is the
Examples of calculating the cycle and response times
Example I
You have installed an S7-400 with the following modules in the central controller:
● a CPU 410–5H in redundant mode
● 2 digital input modules SM 421; DI 32xDC 24 V (each with 4 bytes in the PI)
● 2 digital output modules SM 422; DO 32xDC 24 V/0.5 (each with 4 bytes in the PI)
According to the instruction list, the user program runtime is 15 ms.
Calculating the cycle time
The cycle time for the example results from the following times:
● As the CPU-specific factor is 1.2, the user program execution time is:
approx. 18.0 ms
● Process image transfer time (4 double-word accesses)
Process image: 9 µs + 4 ×25 µs = approx. 0.109 ms
● OS execution time at the scan cycle checkpoint:
approx. 0.31 ms
The total of the listed times is equivalent to the cycle time:
= 18.0 ms + 0.109 ms + 0.31 ms
.
To Next Page
Loading...
Need help?
General
