Cycle and Response Times of the S7-400
9.11 CBA response times
S7-400 Automation System, CPU Specifications
9-28 Manual, 10/2006, 6ES7498-8AA04-8BA0
The following applies:
CBA response times =
Processing time on the transmitting CPU* +
Cycle time based on the configured transmission frequency** +
Processing time on the receiving CPU*
*) Add all input and output interconnections of the CPU to determine the processing time.
You can read the processing time from the diagram based on the determined number of
interconnections and amount of data on them.
**) The configured transmission frequency has a direct relationship to the actual cycle time in
the network. For technical reasons, the cycle time is based on the square of the base cycle
time of 1ms. The actual cycle time therefore corresponds to the next smaller square of the
configure transmission frequency; the following relationships result from the specified values:
(transmission frequency <-> cycle time): 1<->1 | 2<->2 | 5<->4 | 10<->8 | 20<->16 | 50<->32 |
100<->64 | 200<->128 | 500<->256 | 1000<->512
Note on the Processing Times for Cyclic Interconnections
● The processing times are based on 32 remote partners. Few remote partners reduces the
processing times by approx. 0.02 ms per partner.
● The processing times are based on byte interconnections (single bytes or arrays).
● The processing times are applicable for situations in which the same transmission
frequency is configured for all cyclic interconnections. Increased transmission frequency
can improve the performance.
● When acyclic interconnections with the maximum amount of data are simultaneously
active, the response times of the cyclic interconnections increase by approx. 33%.
● The example measurements were performed with a CPU 416-3 PN/DP. With a CPU 414-
3 PN/DP the processing times increase by approx. 20%.
Response Time for Acyclic Interconnections
The resulting response time depends on the configured sampling frequency and the number
of cyclic interconnections that are simultaneously active. You can see three examples for the
resulting response times in the following table.
Table 9-11 Response time for acyclic interconnections
Configured sampling frequency Resulting response time without
cyclic interconnections
Resulting response time with
cyclic interconnections
(maximum amount of data)
200 ms 195 ms 700 ms
500 ms 480 ms 800 ms
1000 ms 950 ms 1050 ms
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