Siemens Simatic S7-1500 Function Manual page 69

Cycle and response times of the S7-1500R/H redundant system
5.4 Response time of R/H CPUs
Determination of cycle and response times
At the end of the cyclic program, the primary CPU waits until the backup CPU too has
acknowledged the end of the cyclic program. The cycle time of the primary CPU therefore
also includes the time lag of the backup CPU. The cycle is extended by the time lag.
Advantages
The fact that the cycle time includes the time lag of the backup CPU to the primary CPU
offers the following advantages:
● By monitoring the maximum cycle time in STEP 7, in the HMI or in the user program after
SYNCUP, it is possible to determine the cycle time for a switchover of the CPUs in case
of an error.
Requirement: You have reset the maximum cycle time after the end of SYNCUP.
● During commissioning it is not necessary to perform complicated tests to determine
whether the required response time can still be complied with if a CPU fails.
● During commissioning and ongoing operation you can estimate whether your automation
task can meet the response times required for the process.
The same functions as those for the non-redundant CPUs are available for determining the
cycle and response times:
Table 5- 2 Functions for determining the cycle and response times
Function
Defining the minimum cycle time and the maximum cycle time in STEP 7
Defining the desired response of the user program if the maximum cycle time
has been exceeded
Reading out the cycle time statistics via STEP 7 and the display of the CPU
Note that this function always shows the cycle time statistics from the primary
CPU viewpoint, even when you go online via the backup CPU.
Reading out the cycle time and reading out the progress in the SYNCUP system
state with the instruction "RT_INFO"
Display of measurements (traces) which record special time-critical signal char-
acteristics
Reading out the progress of the SYNCUP system state using the display of the
CPU
68
Additional information
Section Cycle time (Page 24)
Function manual Using the trace and
logic analyzer functions
(http://support.automation.siemens.com/
WW/view/en/64897128)
S7-1500R/H redundant system
(https://support.industry.siemens.com/c
s/ww/en/view/109754833) system man-
ual
Cycle and response times
Function Manual, 10/2018, A5E03461504-AD